Re: [Python-Dev] Reading Python source file

Well, not quite the same thing, but https://github.com/kirbyfan64/pfbuild/blob/master/pfbuild embeds the compressed version of 16k LOC. Would it be affected negatively in any way be this? Since all the data is on one line, I'd think the old (current) parser would end up reading in the whole line anyway. On November 18, 2015 9:48:41 AM CST, Guido van Rossum wrote:

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On 11/18/2015 03:31 AM, Nick Coghlan wrote:

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That behaviour is then inherited at the command line by both the -m switch and the support for executing directories and zip archives. When we consider that the "-c" switch also executes an in-memory string, direct script execution is currently the odd one out in

*not*

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reading the entire source file into memory first, so Serhiy's

On Wed, Nov 18, 2015 at 4:15 AM, Hrvoje Niksic wrote: proposed

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simplification of the implementation makes sense to me.

Reading the whole script in memory will incur an overhead when executing scripts that contain (potentially large) data embedded after the end of script source.

The technique of reading data from sys.argv[0] is probably obsolete now that Python supports executing zipped archives, but it is popular in shell scripting and might still be used for self-extracting scripts that must support older Python versions. This feature doesn't affect imports and -c which are not expected to contain non-Python data.

That trick doesn't work unless the data looks like Python comments or data (e.g. a docstring). Python has always insisted on being able to parse until EOF. The only extreme case would be a small script followed by e.g. 4 GB of comments (where the old parser would indeed be more efficient). But unless you can point me to an occurrence of this in the wild I'm going to speculate that you just made this up based on the shell analogy (which isn't perfect).

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