[issue19692] Rename Py_SAFE_DOWNCAST

[Antoine Pitrou]

New submission from Antoine Pitrou:

Py_SAFE_DOWNCAST's name is a bit misleading: it isn't safe except in debug mode. I propose to rename it to Py_DOWNCAST, so that developers are reminded that the burden of the sanity checks is on them.

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components: Interpreter Core
messages: 203764
nosy: christian.heimes, haypo, pitrou, tim.peters
priority: normal
severity: normal
status: open
title: Rename Py_SAFE_DOWNCAST
type: enhancement
versions: Python 3.4

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[Christian Heimes]

Christian Heimes added the comment:

+1

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[STINNER Victor]

STINNER Victor added the comment:

I like Py_DOWNCAST name.

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[Antoine Pitrou]

Antoine Pitrou added the comment:

Actually, _Py_DOWNCAST may be better (not a public API).

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[Martin v. Löwis]

Martin v. L?wis added the comment:

-1. The macro name doesn't claim the cast to be safe, i.e. it's not "Py_SAFELY_DOWNCAST", but "safe downcast", i.e. it's an assertion that the cast actually has been verified as being safe.

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nosy: +loewis

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[Antoine Pitrou]

Post by Martin v. Löwis
-1. The macro name doesn't claim the cast to be safe, i.e. it's not
"Py_SAFELY_DOWNCAST", but "safe downcast", i.e. it's an assertion that
the cast actually has been verified as being safe.

It's not an assertion, it's a cast.
Otherwise it should be named Py_ASSERT_SAFE_DOWNCAST (and it should only
do the assertion, not the cast).

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Python tracker <report at bugs.python.org>
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[Tim Peters]

Tim Peters added the comment:

Goodness. Name it

_Py_DOWNCAST_AND_IN_DEBUG_MODE_ASSERT_UPCASTING_THE_RESULT_COMPARES_EQUAL_TO_THE_ORIGINAL_ARGUMENT

;-)

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Python tracker <report at bugs.python.org>
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[Antoine Pitrou]

Antoine Pitrou added the comment:

Well, I obviously won't fight very hard for this one.

But I would like to point out that APIs with "safe" (not "safely" :-)) in their name usually imply that the API is safe, not that the input has been sanitized beforehand.

For example in the stdlib: pprint.saferepr, string.safe_substitute, xmlrpc.client.SafeTransport. In the C API: Py_TRASHCAN_SAFE_BEGIN.

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