SCons_experimental / src / engine / SCons / Script / Main.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!--
__COPYRIGHT__

This file is processed by the bin/SConsDoc.py module.
See its __doc__ string for a discussion of the format.
-->

<!DOCTYPE sconsdoc [
<!ENTITY % scons SYSTEM '../../../../doc/scons.mod'>
%scons;
<!ENTITY % builders-mod SYSTEM '../../../../doc/generated/builders.mod'>
%builders-mod;
<!ENTITY % functions-mod SYSTEM '../../../../doc/generated/functions.mod'>
%functions-mod;
<!ENTITY % tools-mod SYSTEM '../../../../doc/generated/tools.mod'>
%tools-mod;
<!ENTITY % variables-mod SYSTEM '../../../../doc/generated/variables.mod'>
%variables-mod;
]>

<sconsdoc xmlns="http://www.scons.org/dbxsd/v1.0"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0/scons.xsd scons.xsd">


<scons_function name="AddOption">
<arguments signature="global">
(arguments)
</arguments>
<summary>
<para>
This function adds a new command-line option to be recognized.
The specified
<varname>arguments</varname>
are the same as supported by the standard Python
<function>optparse.add_option</function>()
method (with a few additional capabilities noted below);
see the documentation for
<literal>optparse</literal>
for a thorough discussion of its option-processing capabities.
</para>

<para>
In addition to the arguments and values supported by the
<function>optparse.add_option</function>()
method,
the SCons
&f-AddOption;
function allows you to set the
<literal>nargs</literal>
keyword value to
<literal>'?'</literal>
(a string with just the question mark)
to indicate that the specified long option(s) take(s) an
<emphasis>optional</emphasis>
argument.
When
<literal>nargs = '?'</literal>
is passed to the
&f-AddOption;
function, the
<literal>const</literal>
keyword argument
may be used to supply the "default"
value that should be used when the
option is specified on the command line
without an explicit argument.
</para>

<para>
If no
<literal>default=</literal>
keyword argument is supplied when calling
&f-AddOption;,
the option will have a default value of
<literal>None</literal>.
</para>

<para>
Once a new command-line option has been added with
&f-AddOption;,
the option value may be accessed using
&f-GetOption;
or
<function>env.GetOption</function>().
The value may also be set, using
&f-SetOption;
or
<function>env.SetOption</function>(),
if conditions in a
&SConscript;
require overriding any default value.
Note, however, that a
value specified on the command line will
<emphasis>always</emphasis>
override a value set by any SConscript file.
</para>

<para>
Any specified
<literal>help=</literal>
strings for the new option(s)
will be displayed by the
<option>-H</option>
or
<option>-h</option>
options
(the latter only if no other help text is
specified in the SConscript files).
The help text for the local options specified by
&f-AddOption;
will appear below the SCons options themselves,
under a separate
<literal>Local Options</literal>
heading.
The options will appear in the help text
in the order in which the
&f-AddOption;
calls occur.
</para>

<para>
Example:
</para>

<example_commands>
AddOption('--prefix',
          dest='prefix',
          nargs=1, type='string',
          action='store',
          metavar='DIR',
          help='installation prefix')
env = Environment(PREFIX = GetOption('prefix'))
</example_commands>
</summary>
</scons_function>

<scons_function name="GetBuildFailures">
<arguments signature="global">
()
</arguments>
<summary>
<para>
Returns a list of exceptions for the
actions that failed while
attempting to build targets.
Each element in the returned list is a
<classname>BuildError</classname>
object
with the following attributes
that record various aspects
of the build failure:
</para>

<para>
<literal>.node</literal>
The node that was being built
when the build failure occurred.
</para>

<para>
<literal>.status</literal>
The numeric exit status
returned by the command or Python function
that failed when trying to build the
specified Node.
</para>

<para>
<literal>.errstr</literal>
The SCons error string
describing the build failure.
(This is often a generic
message like "Error 2"
to indicate that an executed
command exited with a status of 2.)
</para>

<para>
<literal>.filename</literal>
The name of the file or
directory that actually caused the failure.
This may be different from the
<literal>.node</literal>
attribute.
For example,
if an attempt to build a target named
<filename>sub/dir/target</filename>
fails because the
<filename>sub/dir</filename>
directory could not be created,
then the
<literal>.node</literal>
attribute will be
<filename>sub/dir/target</filename>
but the
<literal>.filename</literal>
attribute will be
<filename>sub/dir</filename>.
</para>

<para>
<literal>.executor</literal>
The SCons Executor object
for the target Node
being built.
This can be used to retrieve
the construction environment used
for the failed action.
</para>

<para>
<literal>.action</literal>
The actual SCons Action object that failed.
This will be one specific action
out of the possible list of
actions that would have been
executed to build the target.
</para>

<para>
<literal>.command</literal>
The actual expanded command that was executed and failed,
after expansion of
&cv-link-TARGET;,
&cv-link-SOURCE;,
and other construction variables.
</para>

<para>
Note that the
&f-GetBuildFailures;
function
will always return an empty list
until any build failure has occurred,
which means that
&f-GetBuildFailures;
will always return an empty list
while the
&SConscript;
files are being read.
Its primary intended use is
for functions that will be
executed before SCons exits
by passing them to the
standard Python
<function>atexit.register</function>()
function.
Example:
</para>

<example_commands>
import atexit

def print_build_failures():
    from SCons.Script import GetBuildFailures
    for bf in GetBuildFailures():
        print "%s failed: %s" % (bf.node, bf.errstr)

atexit.register(print_build_failures)
</example_commands>
</summary>
</scons_function>

<scons_function name="GetOption">
<arguments>
(name)
</arguments>
<summary>
<para>
This function provides a way to query the value of
SCons options set on scons command line
(or set using the
&f-link-SetOption;
function).
The options supported are:
</para>

<para>
<variablelist>
<varlistentry>
<term><literal>cache_debug</literal></term>
<listitem>
<para>
which corresponds to --cache-debug;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>cache_disable</literal></term>
<listitem>
<para>
which corresponds to --cache-disable;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>cache_force</literal></term>
<listitem>
<para>
which corresponds to --cache-force;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>cache_show</literal></term>
<listitem>
<para>
which corresponds to --cache-show;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>clean</literal></term>
<listitem>
<para>
which corresponds to -c, --clean and --remove;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>config</literal></term>
<listitem>
<para>
which corresponds to --config;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>directory</literal></term>
<listitem>
<para>
which corresponds to -C and --directory;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>diskcheck</literal></term>
<listitem>
<para>
which corresponds to --diskcheck
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>duplicate</literal></term>
<listitem>
<para>
which corresponds to --duplicate;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>file</literal></term>
<listitem>
<para>
which corresponds to -f, --file, --makefile and --sconstruct;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>help</literal></term>
<listitem>
<para>
which corresponds to -h and --help;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>ignore_errors</literal></term>
<listitem>
<para>
which corresponds to --ignore-errors;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>implicit_cache</literal></term>
<listitem>
<para>
which corresponds to --implicit-cache;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>implicit_deps_changed</literal></term>
<listitem>
<para>
which corresponds to --implicit-deps-changed;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>implicit_deps_unchanged</literal></term>
<listitem>
<para>
which corresponds to --implicit-deps-unchanged;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>interactive</literal></term>
<listitem>
<para>
which corresponds to --interact and --interactive;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>keep_going</literal></term>
<listitem>
<para>
which corresponds to -k and --keep-going;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>max_drift</literal></term>
<listitem>
<para>
which corresponds to --max-drift;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>no_exec</literal></term>
<listitem>
<para>
which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>no_site_dir</literal></term>
<listitem>
<para>
which corresponds to --no-site-dir;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>num_jobs</literal></term>
<listitem>
<para>
which corresponds to -j and --jobs;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>profile_file</literal></term>
<listitem>
<para>
which corresponds to --profile;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>question</literal></term>
<listitem>
<para>
which corresponds to -q and --question;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>random</literal></term>
<listitem>
<para>
which corresponds to --random;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>repository</literal></term>
<listitem>
<para>
which corresponds to -Y, --repository and --srcdir;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>silent</literal></term>
<listitem>
<para>
which corresponds to -s, --silent and --quiet;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>site_dir</literal></term>
<listitem>
<para>
which corresponds to --site-dir;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>stack_size</literal></term>
<listitem>
<para>
which corresponds to --stack-size;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>taskmastertrace_file</literal></term>
<listitem>
<para>
which corresponds to --taskmastertrace; and
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>warn</literal></term>
<listitem>
<para>
which corresponds to --warn and --warning.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>

<para>
See the documentation for the
corresponding command line object for information about each specific
option.
</para>
</summary>
</scons_function>

<scons_function name="Progress">
<arguments signature="global">
(callable, [interval])
</arguments>
<arguments signature="global">
(string, [interval, file, overwrite])
</arguments>
<arguments signature="global">
(list_of_strings, [interval, file, overwrite])
</arguments>
<summary>
<para>
Allows SCons to show progress made during the build
by displaying a string or calling a function while
evaluating Nodes (e.g. files).
</para>

<para>
If the first specified argument is a Python callable
(a function or an object that has a
<function>__call__</function>()
method),
the function will be called
once every
<varname>interval</varname>
times a Node is evaluated.
The callable will be passed the evaluated Node
as its only argument.
(For future compatibility,
it's a good idea to also add
<literal>*args</literal>
and
<literal>**kw</literal>
as arguments to your function or method.
This will prevent the code from breaking
if SCons ever changes the interface
to call the function with additional arguments in the future.)
</para>

<para>
An example of a simple custom progress function
that prints a string containing the Node name
every 10 Nodes:
</para>

<example_commands>
def my_progress_function(node, *args, **kw):
    print 'Evaluating node %s!' % node
Progress(my_progress_function, interval=10)
</example_commands>

<para>
A more complicated example of a custom progress display object
that prints a string containing a count
every 100 evaluated Nodes.
Note the use of
<literal>\r</literal>
(a carriage return)
at the end so that the string
will overwrite itself on a display:
</para>

<example_commands>
import sys
class ProgressCounter(object):
    count = 0
    def __call__(self, node, *args, **kw):
        self.count += 100
        sys.stderr.write('Evaluated %s nodes\r' % self.count)
Progress(ProgressCounter(), interval=100)
</example_commands>

<para>
If the first argument
&f-link-Progress;
is a string,
the string will be displayed
every
<varname>interval</varname>
evaluated Nodes.
The default is to print the string on standard output;
an alternate output stream
may be specified with the
<literal>file=</literal>
argument.
The following will print a series of dots
on the error output,
one dot for every 100 evaluated Nodes:
</para>

<example_commands>
import sys
Progress('.', interval=100, file=sys.stderr)
</example_commands>

<para>
If the string contains the verbatim substring
&cv-TARGET;,
it will be replaced with the Node.
Note that, for performance reasons, this is
<emphasis>not</emphasis>
a regular SCons variable substition,
so you can not use other variables
or use curly braces.
The following example will print the name of
every evaluated Node,
using a
<literal>\r</literal>
(carriage return) to cause each line to overwritten by the next line,
and the
<literal>overwrite=</literal>
keyword argument to make sure the previously-printed
file name is overwritten with blank spaces:
</para>

<example_commands>
import sys
Progress('$TARGET\r', overwrite=True)
</example_commands>

<para>
If the first argument to
&f-Progress;
is a list of strings,
then each string in the list will be displayed
in rotating fashion every
<varname>interval</varname>
evaluated Nodes.
This can be used to implement a "spinner"
on the user's screen as follows:
</para>

<example_commands>
Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)
</example_commands>
</summary>
</scons_function>

<scons_function name="Precious">
<arguments>
(target, ...)
</arguments>
<summary>
<para>
Marks each given
<varname>target</varname>
as precious so it is not deleted before it is rebuilt. Normally
&scons;
deletes a target before building it.
Multiple targets can be passed in to a single call to
&f-Precious;.
</para>
</summary>
</scons_function>

<scons_function name="SetOption">
<arguments>
(name, value)
</arguments>
<summary>
<para>
This function provides a way to set a select subset of the scons command
line options from a SConscript file. The options supported are:
</para>

<para>
<variablelist>
<varlistentry>
<term><literal>clean</literal></term>
<listitem>
<para>
which corresponds to -c, --clean and --remove;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>duplicate</literal></term>
<listitem>
<para>
which corresponds to --duplicate;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>help</literal></term>
<listitem>
<para>
which corresponds to -h and --help;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>implicit_cache</literal></term>
<listitem>
<para>
which corresponds to --implicit-cache;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>max_drift</literal></term>
<listitem>
<para>
which corresponds to --max-drift;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>no_exec</literal></term>
<listitem>
<para>
which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>num_jobs</literal></term>
<listitem>
<para>
which corresponds to -j and --jobs;
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>random</literal></term>
<listitem>
<para>
which corresponds to --random; and
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>stack_size</literal></term>
<listitem>
<para>
which corresponds to --stack-size.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>

<para>
See the documentation for the
corresponding command line object for information about each specific
option.
</para>

<para>
Example:
</para>

<example_commands>
SetOption('max_drift', 1)
</example_commands>
</summary>
</scons_function>

</sconsdoc>
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