Source

emacs / man / ses.texi

Full commit
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
\input texinfo   @c -*-texinfo-*-
@c %**start of header
@setfilename ../info/ses
@settitle SES: Simple Emacs Spreadsheet
@setchapternewpage off
@c %**end of header

@copying
This file documents SES: the Simple Emacs Spreadsheet.

Copyright @copyright{} 2002  Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover texts being ``A GNU
Manual,'' and with the Back-Cover Texts as in (a) below.  A copy of the
license is included in the section entitled ``GNU Free Documentation
License'' in the Emacs manual.

(a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
this GNU Manual, like GNU software.  Copies published by the Free
Software Foundation raise funds for GNU development.''

This document is part of a collection distributed under the GNU Free
Documentation License.  If you want to distribute this document
separately from the collection, you can do so by adding a copy of the
license to the document, as described in section 6 of the license.
@end quotation
@end copying

@dircategory Emacs
@direntry
* SES: (ses).       Simple Emacs Spreadsheet
@end direntry

@finalout

@titlepage
@title SES
@subtitle Simple Emacs Spreadsheet
@author Jonathan A. Yavner
@author @email{jyavner@@member.fsf.org}

@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@c ===================================================================

@ifnottex
@node Top, Sales Pitch, (dir), (dir)
@comment  node-name,  next,  previous,  up
@top SES: Simple Emacs Spreadsheet

@display
SES is a major mode for GNU Emacs to edit spreadsheet files, which
contain a rectangular grid of cells.  The cells' values are specified
by formulas that can refer to the values of other cells.
@end display
@end ifnottex

To report bugs, send email to @email{jyavner@@member.fsf.org}.

@menu
* Sales Pitch::                 Why use SES?
* The Basics::                  Basic spreadsheet commands
* Advanced Features::           Want to know more?
* For Gurus::                   Want to know @emph{even more}?
* Acknowledgements::            Acknowledgements
@end menu

@c ===================================================================

@node Sales Pitch, The Basics, Top, Top
@comment  node-name,  next,  previous,  up
@chapter Sales Pitch

@itemize @bullet
@item Create and edit simple spreadsheets with a minimum of fuss.
@item Full undo/redo/autosave.
@item Immune to viruses in spreadsheet files.
@item Cell formulas are straight Emacs Lisp.
@item Printer functions for control of cell appearance.
@item Intuitive keystroke commands: C-o = insert row, M-o = insert column, etc.
@item ``Spillover'' of lengthy cell values into following blank cells.
@item Header line shows column letters or a selected row.
@item Completing-read for entering symbols as cell values.
@item Cut, copy, and paste can transfer formulas and printer functions.
@item Import and export of tab-separated values or tab-separated formulas.
@item Plaintext, easily-hacked file format.
@end itemize

@c ===================================================================

@node The Basics, Advanced Features, Sales Pitch, Top
@comment  node-name,  next,  previous,  up
@chapter The Basics

A @dfn{cell identifier} is a symbol with a column letter and a row
number.  Cell B7 is the 2nd column of the 7th row.  For very wide
spreadsheets, there are two column letters: cell AB7 is the 28th
column of the 7th row.

@table @kbd
@item j
Moves point to cell, specified by identifier (@code{ses-jump}).
@end table

Point is always at the left edge of a cell, or at the empty endline.
When mark is inactive, the current cell is underlined.  When mark is
active, the range is the highlighted rectangle of cells (SES always
uses transient mark mode).  Drag the mouse from A1 to A3 to create the
range A1-A2.  Many SES commands operate only on single cells, not
ranges.

@table @kbd
@item C-SPC
@itemx C-@@
Set mark at point (@code{set-mark-command}).

@item C-g
Turn off the mark (@code{keyboard-quit}).

@item M-h
Highlight current row (@code{ses-mark-row}).

@item S-M-h
Highlight current column (@code{ses-mark-column}).

@item C-x h
Highlight all cells (@code{mark-whole-buffer}).
@end table

@menu
* Formulas::
* Resizing::
* Printer functions::
* Clearing cells::
* Copy/cut/paste::
* Customizing SES::
@end menu

@node Formulas, Resizing, The Basics, The Basics
@section Cell formulas

To enter a number into the current cell, just start typing:

@table @kbd
@item 0..9
Self-insert a digit (@code{ses-read-cell}).

@item -
Self-insert a negative number (@code{ses-read-cell}).

@item .
Self-insert a fractional number (@code{ses-read-cell}).

@item "
Self-insert a quoted string.  The ending double-quote
is inserted for you (@code{ses-read-cell}).

@item (
Self-insert an expression.  The right-parenthesis is inserted for you
(@code{ses-read-cell}).  To access another cell's value, just use its
identifier in your expression.  Whenever the other cell is changed,
this cell's formula will be reevaluated.  While typing in the
expression, you can use @kbd{M-TAB} to complete symbol names.

@item ' @r{(apostrophe)}
Enter a symbol (ses-read-symbol).  SES remembers all symbols that have
been used as formulas, so you can type just the beginning of a symbol
and use @kbd{SPC}, @kbd{TAB}, and @kbd{?} to complete it.
@end table

To enter something else (e.g., a vector), begin with a digit, then
erase the digit and type whatever you want.

@table @kbd
@item RET
Edit the existing formula in the current cell (@code{ses-edit-cell}).

@item C-c C-c
Force recalculation of the current cell or range (@code{ses-recalculate-cell}).

@item C-c C-l
Recalculate the entire spreadsheet (@code{ses-recalculate-all}).
@end table

@node Resizing, Printer functions, Formulas, The Basics
@section Resizing the spreadsheet

Basic commands:

@table @kbd
@item C-o
(@code{ses-insert-row})

@item M-o
(@code{ses-insert-column})

@item C-k
(@code{ses-delete-row})

@item M-k
(@code{ses-delete-column})

@item w
(@code{ses-set-column-width})

@item TAB
Moves point to the next rightward cell, or inserts a new column if
already at last cell on line, or inserts a new row if at endline
(@code{ses-forward-or-insert}).

@item C-j
Linefeed inserts below the current row and moves to column A
(@code{ses-append-row-jump-first-column}).
@end table

Resizing the spreadsheet (unless you're just changing a column width)
relocates all the cell-references in formulas so they still refer to
the same cells.  If a formula mentioned B1 and you insert a new first
row, the formula will now mention B2.

If you delete a cell that a formula refers to, the cell-symbol is
deleted from the formula, so @code{(+ A1 B1 C1)} after deleting the third
column becomes @code{(+ A1 B1)}.  In case this is not what you wanted:

@table @kbd
@item C-_
@itemx C-x u
Undo previous action (@code{(undo)}).
@end table


@node Printer functions, Clearing cells, Resizing, The Basics
@section Printer functions

Printer functions convert binary cell values into the print forms that
Emacs will display on the screen.

A printer can be a format string, like @samp{"$%.2f"}.  The result
string is right-aligned within the print cell.  To get left-alignment,
use parentheses: @samp{("$%.2f")}.  A printer can also be a
one-argument function (a symbol or a lambda), whose result is a string
(right-aligned) or list of one string (left-aligned).  While typing in
a lambda, you can use @kbd{M-TAB} to complete the names of symbols.

Each cell has a printer.  If @code{nil}, the column-printer for the cell's
column is used.  If that is also @code{nil}, the default-printer for the
spreadsheet is used.

@table @kbd
@item p
Enter a printer for current cell or range (@code{ses-read-cell-printer}).

@item M-p
Enter a printer for the current column (@code{ses-read-column-printer}).

@item C-c C-p
Enter the default printer for the spreadsheet
(@code{ses-read-default-printer}).
@end table

The @code{ses-read-@r{XXX}-printer} commands have their own minibuffer
history, which is preloaded with the set of all printers used in this
spreadsheet, plus the standard printers.

The standard printers are suitable only for cells, not columns or
default, because they format the value using the column-printer (or
default-printer if @code{nil}) and then center the result:

@table @code
@item ses-center
Just centering.

@item ses-center-span
Centering with spill-over to following blank cells.

@item ses-dashfill
Centering using dashes (-) instead of spaces.

@item ses-dashfill-span
Centering with dashes and spill-over.

@item ses-tildefill-span
Centering with tildes (~) and spill-over.
@end table


@node Clearing cells, Copy/cut/paste, Printer functions, The Basics
@section Clearing cells

These commands set both formula and printer to @code{nil}:

@table @kbd
@item DEL
Clear cell and move left (@code{ses-clear-cell-backward}).

@item C-d
Clear cell and move right (@code{ses-clear-cell-forward}).
@end table


@node Copy/cut/paste, Customizing SES, Clearing cells, The Basics
@section Copy, cut, and paste

The copy functions work on rectangular regions of cells.  You can paste the
copies into non-SES buffers to export the print text.

@table @kbd
@item M-w
@itemx [copy]
@itemx [C-insert]
Copy the highlighted cells to kill ring and primary clipboard
(@code{kill-ring-save}).

@item [drag-mouse-1]
Mark a region and copy it to kill ring and primary clipboard
(@code{mouse-set-region}).

@item [M-drag-mouse-1]
Mark a region and copy it to kill ring and secondary clipboard
(@code{mouse-set-secondary}).

@item C-w
@itemx [cut]
@itemx [S-delete]
The cut functions do not actually delete rows or columns---they copy
and then clear (@code{ses-kill-override}).

@item C-y
@itemx [S-insert]
Paste from kill ring (@code{yank}).  The paste functions behave
differently depending on the format of the text being inserted:
@itemize @bullet
@item
When pasting cells that were cut from a SES buffer, the print text is
ignored and only the attached formula and printer are inserted; cell
references in the formula are relocated unless you use @kbd{C-u}.
@item
The pasted text overwrites a rectangle of cells whose top left corner
is the current cell.  If part of the rectangle is beyond the edges of
the spreadsheet, you must confirm the increase in spreadsheet size.
@item
Non-SES text is usually inserted as a replacement formula for the
current cell.  If the formula would be a symbol, it's treated as a
string unless you use @kbd{C-u}.  Pasted formulas with syntax errors
are always treated as strings.
@end itemize

@item [paste]
Paste from primary clipboard or kill ring (@code{clipboard-yank}).

@item [mouse-2]
Set point and paste from primary clipboard (@code{mouse-yank-at-click}).

@item [M-mouse-2]
Set point and paste from secondary clipboard (@code{mouse-yank-secondary}).

@item M-y
Immediately after a paste, you can replace the text with a preceding
element from the kill ring (@code{ses-yank-pop}).  Unlike the standard
Emacs yank-pop, the SES version uses @code{undo} to delete the old
yank.  This doesn't make any difference?
@end table

@node Customizing SES,  , Copy/cut/paste, The Basics
@section Customizing SES

By default, a newly-created spreadsheet has 1 row and 1 column.  The
column width is 7 and the default printer is @samp{"%.7g"}.  Each of these
can be customized.  Look in group ``ses''.

After entering a cell value, point normally moves right to the next
cell.  You can customize @code{ses-after-entry-functions} to move left or
up or down.  For diagonal movement, select two functions from the
list.

@code{ses-mode-hook} is a normal mode hook (list of functions to
execute when starting SES mode for a buffer).

The variable @code{safe-functions} is a list of possibly-unsafe
functions to be treated as safe when analysing formulas and printers.
@xref{Virus protection}.  Before customizing @code{safe-functions},
think about how much you trust the person who's suggesting this
change.  The value @code{t} turns off all anti-virus protection.  A
list-of-functions value might enable a ``gee whiz'' spreadsheet, but it
also creates trapdoors in your anti-virus armor.  In order for virus
protection to work, you must always press @kbd{n} when presented with
a virus warning, unless you understand what the questionable code is
trying to do.  Do not listen to those who tell you to customize
@code{enable-local-eval}---this variable is for people who don't wear
safety belts!


@c ===================================================================

@node Advanced Features, For Gurus, The Basics, Top
@chapter Advanced Features

@table @kbd
@item C-c M-C-h
(@code{ses-set-header-row}).  The header line at the top of the SES
window normally shows the column letter for each column.  You can set
it to show a copy of some row, such as a row of column titles, so that
row will always be visible.  Default is to set the current row as the
header; use C-u to prompt for header row.  Set the header to row 0 to
show column letters again.
@item [header-line mouse-3]
Pops up a menu to set the current row as the header, or revert to
column letters.
@end table

@menu
* The print area::
* Ranges in formulas::
* Sorting by column::
* Standard formula functions::
* More on cell printing::
* Import and export::
* Virus protection::
* Spreadsheets with details and summary::
@end menu

@node The print area, Ranges in formulas, Advanced Features, Advanced Features
@section The print area

A SES file consists of a print area and a data area.  Normally the
buffer is narrowed to show only the print area.  The print area is
read-only except for special SES commands; it contains cell values
formatted by printer functions.  The data area records the formula and
printer functions, etc.

@table @kbd
@item C-x n w
Show print and data areas (@code{widen}).

@item C-c C-n
Show only print area (@code{ses-renarrow-buffer}).

@item S-C-l
@itemx M-C-l
Recreate print area by reevaluating printer functions for all cells
(@code{ses-reprint-all}).
@end table

@node Ranges in formulas, Sorting by column, The print area, Advanced Features
@section Ranges in formulas

A formula like
@lisp
(+ A1 A2 A3)
@end lisp
is the sum of three specific cells.  If you insert a new second row,
the formula becomes
@lisp
(+ A1 A3 A4)
@end lisp
and the new row is not included in the sum.

The macro @code{(ses-range @var{from} @var{to})} evalutes to a list of
the values in a rectangle of cells.  If your formula is
@lisp
(apply '+ (ses-range A1 A3))
@end lisp
and you insert a new second row, it becomes
@lisp
(apply '+ (ses-range A1 A4))
@end lisp
and the new row is included in the sum.

While entering or editing a formula in the minibuffer, you can select
a range in the spreadsheet (using mouse or keyboard), then paste a
representation of that range into your formula.  Suppose you select
A1-C1:

@table @kbd
@item [S-mouse-3]
Inserts "A1 B1 C1" @code{(ses-insert-range-click})

@item C-c C-r
Keyboard version (@code{ses-insert-range}).

@item [C-S-mouse-3]
Inserts "(ses-range A1 C1)" (@code{ses-insert-ses-range-click}).

@item C-c C-s
Keyboard version (@code{ses-insert-ses-range}).
@end table

If you delete the @var{from} or @var{to} cell for a range, the nearest
still-existing cell is used instead.  If you delete the entire range,
the formula relocator will delete the ses-range from the formula.

If you insert a new row just beyond the end of a one-column range, or
a new column just beyond a one-row range, the new cell is included in
the range.  New cells inserted just before a range are not included.


@node Sorting by column, Standard formula functions, Ranges in formulas, Advanced Features
@section Sorting by column

@table @kbd
@item C-c M-C-s
Sort the cells of a range using one of the columns
(@code{ses-sort-column}).  The rows (or partial rows if the range
doesn't include all columns) are rearranged so the chosen column will
be in order.

@item [header-line mouse-2]
The easiest way to sort is to click mouse-2 on the chosen column's header row
(@code{ses-sort-column-click}).
@end table

The sort comparison uses @code{string<}, which works well for
right-justified numbers and left-justified strings.

With prefix arg, sort is in descending order.

Rows are moved one at a time, with relocation of formulas.  This works
well if formulas refer to other cells in their row, not so well for
formulas that refer to other rows in the range or to cells outside the
range.


@node Standard formula functions, More on cell printing, Sorting by column, Advanced Features
@section Standard formula functions

Oftentimes you want a calculation to exclude the blank cells.  Here
are some useful functions to call from your formulas:

@table @code
@item (ses-delete-blanks &rest @var{args})
Returns a list from which all blank cells (value is either @code{nil} or
'*skip*) have been deleted.

@item (ses+ &rest @var{args})
Sum of non-blank arguments.

@item (ses-average @var{list})
Average of non-blank elements in @var{list}.  Here the list is passed
as a single argument, since you'll probably use it with @code{ses-range}.
@end table

@node More on cell printing, Import and export, Standard formula functions, Advanced Features
@section More on cell printing

Special cell values:
@itemize
@item nil prints the same as "", but allows previous cell to spill over.
@item '*skip* replaces nil when the previous cell actually does spill over;
nothing is printed for it.
@item '*error* indicates that the formula signalled an error instead of
producing a value: the print cell is filled with hash marks (#).
@end itemize

If the result from the printer function is too wide for the cell and
the following cell is @code{nil}, the result will spill over into the
following cell.  Very wide results can spill over several cells.  If
the result is too wide for the available space (up to the end of the
row or the next non-@code{nil} cell), the result is truncated if the cell's
value is a string, or replaced with hash marks otherwise.

SES could get confused by printer results that contain newlines or
tabs, so these are replaced with question marks.

@table @kbd
@item C-c C-t
Confine a cell to its own column (@code{ses-truncate-cell}).  This
alows you to move point to a rightward cell that would otherwise be
covered by a spill-over.  If you don't change the rightward cell, the
confined cell will spill over again the next time it is reprinted.

@item C-c C-c
When applied to a single cell, this command displays in the echo area any
formula error or printer error that occurred during
recalculation/reprinting (@code{ses-recalculate-cell}).
@end table

When a printer function signals an error, the default printer
@samp{"%s"} is substituted.  This is useful when your column printer
is numeric-only and you use a string as a cell value.


@node Import and export, Virus protection, More on cell printing, Advanced Features
@section Import and export

@table @kbd
@item x t
Export a range of cells as tab-separated values (@code{ses-export-tsv}).
@item x T
Export a range of cells as tab-separated formulas (@code{ses-export-tsf}).
@end table

The exported text goes to the kill ring --- you can paste it into
another buffer.  Columns are separated by tabs, rows by newlines.

To import text, use any of the yank commands where the text to paste
contains tabs and/or newlines.  Imported formulas are not relocated.

@node Virus protection, Spreadsheets with details and summary, Import and export, Advanced Features
@section Virus protection

Whenever a formula or printer is read from a file or is pasted into
the spreadsheet, it receives a ``needs safety check'' marking.  Later,
when the formula or printer is evaluated for the first time, it is
checked for safety using the @code{unsafep} predicate; if found to be
``possibly unsafe'', the questionable formula or printer is displayed
and you must press Y to approve it or N to use a substitute.  The
substitute always signals an error.

Formulas or printers that you type in are checked immediately for
safety.  If found to be possibly unsafe and you press N to disapprove,
the action is cancelled and the old formula or printer will remain.

Besides viruses (which try to copy themselves to other files),
@code{unsafep} can also detect all other kinds of Trojan horses, such as
spreadsheets that delete files, send email, flood Web sites, alter
your Emacs settings, etc.

Generally, spreadsheet formulas and printers are simple things that
don't need to do any fancy computing, so all potentially-dangerous
parts of the Emacs Lisp environment can be excluded without cramping
your style as a formula-writer.  See the documentation in @file{unsafep.el}
for more info on how Lisp forms are classified as safe or unsafe.

@node Spreadsheets with details and summary,  , Virus protection, Advanced Features
@section Spreadsheets with details and summary

A common organization for spreadsheets is to have a bunch of ``detail''
rows, each perhaps describing a transaction, and then a set of
``summary'' rows that each show reduced data for some subset of the
details.  SES supports this organization via the @code{ses-select}
function.

@table @code
@item (ses-select @var{fromrange} @var{test} @var{torange})
Returns a subset of @var{torange}.  For each member in @var{fromrange}
that is equal to @var{test}, the corresponding member of @var{torange}
is included in the result.
@end table

Example of use:
@lisp
(ses-average (ses-select (ses-range A1 A5) 'Smith (ses-range B1 B5)))
@end lisp
This computes the average of the B column values for those rows whose
A column value is the symbol 'Smith.

Arguably one could specify only @var{fromrange} plus
@var{to-row-offset} and @var{to-column-offset}.  The @var{torange} is
stated explicitly to ensure that the formula will be recalculated if
any cell in either range is changed.

File @file{etc/ses-example.el} in the Emacs distribution is an example of a
details-and-summary spreadsheet.


@c ===================================================================

@node For Gurus, Acknowledgements, Advanced Features, Top
@chapter For Gurus

@menu
* Deferred updates::
* Nonrelocatable references::
* The data area::
* Buffer-local variables in spreadsheets::
* Uses of defadvice in SES::
@end menu

@node Deferred updates, Nonrelocatable references, For Gurus, For Gurus
@section Deferred updates

To save time by avoiding redundant computations, cells that need
recalculation due to changes in other cells are added to a set.  At
the end of the command, each cell in the set is recalculated once.
This can create a new set of cells that need recalculation.  The
process is repeated until either the set is empty or it stops changing
(due to circular references among the cells).  In extreme cases, you
might see progress messages of the form ``Recalculating... (@var{nnn}
cells left)''.  If you interrupt the calculation using @kbd{C-g}, the
spreadsheet will be left in an inconsistent state, so use @kbd{C-_} or
@kbd{C-c C-l} to fix it.

To save even more time by avoiding redundant writes, cells that have
changes are added to a set instead of being written immediately to the
data area.  Each cell in the set is written once, at the end of the
command.  If you change vast quantities of cells, you might see a
progress message of the form ``Writing... (@var{nnn} cells left)''.
These deferred cell-writes cannot be interrupted by @kbd{C-g}, so
you'll just have to wait.

SES uses @code{run-with-idle-timer} to move the cell underline when
Emacs will be scrolling the buffer after the end of a command, and
also to narrow and underline after @kbd{C-x C-v}.  This is visible as
a momentary glitch after C-x C-v and certain scrolling commands.  You
can type ahead without worrying about the glitch.


@node Nonrelocatable references, The data area, Deferred updates, For Gurus
@section Nonrelocatable references

@kbd{C-y} relocates all cell-references in a pasted formula, while
@kbd{C-u C-y} relocates none of the cell-references.  What about mixed
cases?

You can use
@lisp
(symbol-value 'B3)
@end lisp
to make an @dfn{absolute reference}.  The formula relocator skips over
quoted things, so this will not be relocated when pasted or when
rows/columns are inserted/deleted.  However, B3 will not be recorded
as a dependency of this cell, so this cell will not be updated
automatically when B3 is changed.

The variables @code{row} and @code{col} are dynamically bound while a
cell formula is being evaluated.  You can use
@lisp
(ses-cell-value row 0)
@end lisp
to get the value from the leftmost column in the current row.  This
kind of dependency is also not recorded.


@node The data area, Buffer-local variables in spreadsheets, Nonrelocatable references, For Gurus
@section The data area

Begins with an 014 character, followed by sets of cell-definition
macros for each row, followed by column-widths, column-printers,
default-printer, and header-row.  Then there's the global parameters
(file-format ID, numrows, numcols) and the local variables (specifying
SES mode for the buffer, etc.)

When a SES file is loaded, first the numrows and numcols values are
loaded, then the entire data area is @code{eval}ed, and finally the local
variables are processed.

You can edit the data area, but don't insert or delete any newlines
except in the local-variables part, since SES locates things by
counting newlines.  Use @kbd{C-x C-e} at the end of a line to install
your edits into the spreadsheet data structures (this does not update
the print area, use e.g. @kbd{C-c C-l} for that).

The data area is maintained as an image of spreadsheet data
structures that area stored in buffer-local variables.  If the data
area gets messed up, you can try reconstructing the data area from the
data structures:

@table @kbd
@item C-c M-C-l
(@code{ses-reconstruct-all}).
@end table


@node Buffer-local variables in spreadsheets, Uses of defadvice in SES, The data area, For Gurus
@section Buffer-local variables in spreadsheets

You can add additional local variables to the list at the bottom of
the data area, such as hidden constants you want to refer to in your
formulas.

You can override the variable @code{symbolic-formulas} to be a list of
symbols (as parenthesized strings) to show as completions for the '
command.  This initial completions list is used instead of the actual
set of symbols-as-formulas in the spreadsheet.

For examples of these, see file @file{etc/ses-example.ses}.

If (for some reason) you want your formulas or printers to save data
into variables, you must declare these variables as buffer-locals in
order to avoid a virus warning.

You can define functions by making them values for the fake local
variable @code{eval}.  Such functions can then be used in your
formulas and printers, but usually each @code{eval} is presented to
the user during file loading as a potential virus --- this can get
annoying.

You can define functions in your @file{.emacs} file.  Other people can
still read the print area of your spreadsheet, but they won't be able
to recalculate or reprint anything that depends on your functions.  To
avoid virus warnings, each function used in a formula needs
@lisp
(put 'your-function-name 'safe-function t)
@end lisp

@node Uses of defadvice in SES,  , Buffer-local variables in spreadsheets, For Gurus
@section Uses of defadvice in SES

@table @code
@item undo-more
Defines a new undo element format (@var{fun} . @var{args}), which
means ``undo by applying @var{fun} to @var{args}''.  For spreadsheet
buffers, it allows undos in the data area even though that's outside
the narrowing.

@item copy-region-as-kill
When copying from the print area of a spreadsheet, treat the region as
a rectangle and attach each cell's formula and printer as 'ses
properties.

@item yank
When yanking into the print area of a spreadsheet, first try to yank
as cells (if the yank text has 'ses properties), then as tab-separated
formulas, then (if all else fails) as a single formula for the current
cell.
@end table


@c ===================================================================

@node Acknowledgements,  , For Gurus, Top
@chapter Acknowledgements

Coding by:
@quotation
Jonathan Yavner @email{jyavner@@member.fsf.org}@*
Stefan Monnier @email{monnier@@gnu.org}
@end quotation

Ideas from:
@quotation
Christoph Conrad @email{christoph.conrad@@gmx.de}@*
CyberBob @email{cyberbob@@redneck.gacracker.org}@*
Syver Enstad @email{syver-en@@online.no}@*
Ami Fischman @email{fischman@@zion.bpnetworks.com}@*
Thomas Gehrlein @email{Thomas.Gehrlein@@t-online.de}@*
Chris F.A. Johnson @email{c.f.a.johnson@@rogers.com}@*
Yusong Li @email{lyusong@@hotmail.com}@*
Juri Linkov @email{juri@@jurta.org}@*
Harald Maier @email{maierh@@myself.com}@*
Alan Nash @email{anash@@san.rr.com}@*
Fran�ois Pinard @email{pinard@@iro.umontreal.ca}@*
Pedro Pinto @email{ppinto@@cs.cmu.edu}@*
Stefan Reich�r @email{xsteve@@riic.at}@*
Oliver Scholz @email{epameinondas@@gmx.de}@*
Richard M. Stallman @email{rms@@gnu.org}@*
Luc Teirlinck @email{teirllm@@dms.auburn.edu}@*
J. Otto Tennant @email{jotto@@pobox.com}@*
Jean-Philippe Theberge @email{jphil@@acs.pagesjaunes.fr}
@end quotation

@c ===================================================================

@bye

@ignore
   arch-tag: 10a4ee1c-7ef4-4c06-8b7a-f975e39f0dec
@end ignore