pydoc.py doesn't detect IronPython, help(foo) can hang

[owlmonkey]

BPO	19453
Nosy	@tjguk, @jdhardy, @zware, @zooba

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2013-10-30.17:15:13.183>
labels = ['type-bug', 'OS-windows']
title = "pydoc.py doesn't detect IronPython, help(foo) can hang"
updated_at = <Date 2018-07-11.10:15:38.154>
user = 'https://bugs.python.org/owlmonkey'

bugs.python.org fields:

activity = <Date 2018-07-11.10:15:38.154>
actor = 'BreamoreBoy'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Windows']
creation = <Date 2013-10-30.17:15:13.183>
creator = 'owlmonkey'
dependencies = []
files = []
hgrepos = []
issue_num = 19453
keywords = []
message_count = 2.0
messages = ['201750', '228393']
nosy_count = 5.0
nosy_names = ['tim.golden', 'jeff.hardy', 'zach.ware', 'steve.dower', 'owlmonkey']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue19453'
versions = ['Python 2.7']

[owlmonkey]

The pager functions used by help() in StdLib's pydoc.py don't detect IronPython correctly and the result is a lack of functionality or in some cases a hang. This is similar to bpo-8110 in that the code attempts to detect windows with a check for "win32" from sys.platform and needs to check for "cli" as well to detect IronPython running on mono on linux/mac os or on windows.

My naive change to workaround the problem was to add the two line test for "cli" amidst getpager() here:

    if sys.platform == 'win32' or sys.platform.startswith('os2'):
        return lambda text: tempfilepager(plain(text), 'more <')
    if sys.platform == 'cli':
        return plainpager # IronPython
    if hasattr(os, 'system') and os.system('(less) 2>/dev/null') == 0:
        return lambda text: pipepager(text, 'less')

That two line addition allowed basic function and prevents the hang though maybe there is a better pager type that would work on IronPython. In our linux and windows tests though neither the tempfilepager nor pipepager would function on either platform.

I submitted the report to the IronPython issues tracker and someone there suggested posting the patch here.

[BreamoreBoy]

There's a two line patch inline in msg201750. If it's acceptable I'll do a formal patch myself unless someone else wants to pick this up.