sage_setup: Proper error checking for makedirs

[mkoeppe]

If the Python function makedirs is used to achieve the effect of mkdir -p, one needs to distinguish two situations: Directory already exists; directory does not exist and cannot be created.

Current code in sage_setup does not raise an error in the latter situation. Noticed while working on #21469 (VPATH).

See https://stackoverflow.com/questions/600268/mkdir-p-functionality-in-python

CC: @jhpalmieri @jdemeyer @embray

Component: build

Author: Matthias Koeppe

Branch/Commit: 01c3b38

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/23774

[mkoeppe]

Branch: u/mkoeppe/sage_setup__proper_error_checking_for_makedirs

[mkoeppe]

Author: Matthias Koeppe

[mkoeppe]

Commit: 86f742b

[mkoeppe]

New commits:

86f742b

sage_setup: Better error checking for makedirs

[jdemeyer]

comment:3

I prefer a simpler

if not os.path.isdir(path):
    raise

in the except block. Why do you need to check in addition the errno?

[mkoeppe]

comment:4

I'd say not checking the errno is the moral equivalent of catching all exceptions.

[fchapoton]

comment:5

does not build ("path" is not defined..)

[jdemeyer]

comment:6

Replying to @mkoeppe:

I'd say not checking the errno is the moral equivalent of catching all exceptions.

It's fine to catch all exceptions because I suggest to check the desired result not the reason why it failed.

[sagetrac-git]

Changed commit from 86f742b to 1970398

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

1970398

Fix and simplify last change

[jdemeyer]

comment:8

Obvious simplification: change

if condition:
    pass
else:
    raise

to

if not condition:
    raise

[sagetrac-git]

Changed commit from 1970398 to 7e05ec6

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

7e05ec6

Further jeroenification

[jdemeyer]

Changed branch from u/mkoeppe/sage_setup__proper_error_checking_for_makedirs to u/jdemeyer/sage_setup__proper_error_checking_for_makedirs

[jdemeyer]

comment:11

I don't like your last commit message, so I squashed these commits to one.

---

New commits:

01c3b38

sage_setup: Better error checking for makedirs

[jdemeyer]

Changed commit from 7e05ec6 to 01c3b38

[jdemeyer]

Reviewer: Jeroen Demeyer

[vbraun]

Changed branch from u/jdemeyer/sage_setup__proper_error_checking_for_makedirs to 01c3b38