Load Python, Sage, Cython, Fortran and Magma files in Sage

sage.repl.load.is_loadable_filename(filename)

Return whether a file can be loaded into Sage.

This checks only whether its name ends in one of the supported extensions .py, .pyx, .sage, .spyx, .f, .f90 and .m.

Note

load() assumes that \(.m\) signifies a Magma file.

INPUT:

  • filename – a string

OUTPUT:

  • a boolean

EXAMPLES:

sage: sage.repl.load.is_loadable_filename('foo.bar')
False
sage: sage.repl.load.is_loadable_filename('foo.c')
False
sage: sage.repl.load.is_loadable_filename('foo.sage')
True
sage: sage.repl.load.is_loadable_filename('FOO.F90')
True
sage: sage.repl.load.is_loadable_filename('foo.m')
True
sage.repl.load.load(filename, globals, attach=False)

Execute a file in the scope given by globals. If the name starts with http:// or https://, it is treated as a URL and downloaded.

Note

For Cython files, the situation is more complicated – the module is first compiled to a temporary module t and executed via:

from t import *

INPUT:

  • filename – a string denoting a filename or URL.

  • globals – a string:object dictionary; the context in which to execute the file contents.

  • attach – a boolean (default: False); whether to add the file to the list of attached files.

Loading an executable Sage script from the command prompt will run whatever code is inside an

if __name__ == “__main__”:

section, as the condition on __name__ will hold true (code run from the command prompt is considered to be running in the __main__ module.)

EXAMPLES:

Note that .py files are not preparsed:

sage: t = tmp_filename(ext='.py')
sage: with open(t, 'w') as f:
....:     _ = f.write("print(('hi', 2^3)); z = -2^7")
sage: z = 1
sage: sage.repl.load.load(t, globals())
('hi', 1)
sage: z
-7

A .sage file is preparsed:

sage: t = tmp_filename(ext='.sage')
sage: with open(t, 'w') as f:
....:     _ = f.write("print(('hi', 2^3)); z = -2^7")
sage: z = 1
sage: sage.repl.load.load(t, globals())
('hi', 8)
sage: z
-128

Cython files are not preparsed:

sage: t = tmp_filename(ext='.pyx')
sage: with open(t, 'w') as f:
....:     _ = f.write("print(('hi', 2^3)); z = -2^7")
sage: z = 1
sage: sage.repl.load.load(t, globals())
Compiling ...
('hi', 1)
sage: z
-7

If the file is not a Cython, Python, or Sage file, a ValueError is raised:

sage: sage.repl.load.load(tmp_filename(ext=".foo"), globals())
Traceback (most recent call last):
...
ValueError: unknown file extension '.foo' for load or attach (supported extensions: .py, .pyx, .sage, .spyx, .f, .f90, .m)

We load a file given at a remote URL (not tested for security reasons):

sage: sage.repl.load.load('https://www.sagemath.org/files/loadtest.py', globals())  # not tested
hi from the net
5

We can load files using secure http (https):

sage: sage.repl.load.load('https://raw.githubusercontent.com/sagemath/sage-patchbot/3.0.0/sage_patchbot/util.py', globals())  # optional - internet

We attach a file:

sage: t = tmp_filename(ext='.py')
sage: with open(t, 'w') as f:
....:     _ = f.write("print('hello world')")
sage: sage.repl.load.load(t, globals(), attach=True)
hello world
sage: t in attached_files()
True

You cannot attach remote URLs (yet):

sage: sage.repl.load.load('https://www.sagemath.org/files/loadtest.py', globals(), attach=True)  # optional - internet
Traceback (most recent call last):
...
NotImplementedError: you cannot attach a URL

The default search path for loading and attaching files is the current working directory, i.e., '.'. But you can modify the path with load_attach_path():

sage: sage.repl.attach.reset(); reset_load_attach_path()
sage: load_attach_path()
['.']
sage: t_dir = tmp_dir()
sage: fname = 'test.py'
sage: fullpath = os.path.join(t_dir, fname)
sage: with open(fullpath, 'w') as f:
....:     _ = f.write("print(37 * 3)")
sage: load_attach_path(t_dir, replace=True)
sage: attach(fname)
111
sage: sage.repl.attach.reset(); reset_load_attach_path() # clean up

or by setting the environment variable SAGE_LOAD_ATTACH_PATH to a colon-separated list before starting Sage:

$ export SAGE_LOAD_ATTACH_PATH="/path/to/my/library:/path/to/utils"
$ sage
sage: load_attach_path()          # not tested
['.', '/path/to/my/library', '/path/to/utils']
sage.repl.load.load_cython(name)

Helper function to load a Cython file.

INPUT:

  • name – filename of the Cython file

OUTPUT:

  • A string with Python code to import the names from the compiled module.

sage.repl.load.load_wrap(filename, attach=False)

Encode a load or attach command as valid Python code.

INPUT:

  • filename - a string; the argument to the load or attach command

  • attach - a boolean (default: False); whether to attach filename, instead of loading it

OUTPUT:

  • a string

EXAMPLES:

sage: sage.repl.load.load_wrap('foo.py', True)
'sage.repl.load.load(sage.repl.load.base64.b64decode("Zm9vLnB5"),globals(),True)'
sage: sage.repl.load.load_wrap('foo.sage')
'sage.repl.load.load(sage.repl.load.base64.b64decode("Zm9vLnNhZ2U="),globals(),False)'
sage: m = sage.repl.load.base64.b64decode("Zm9vLnNhZ2U=")
sage: m == b'foo.sage'
True