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bug#8711: 24.0.50; binding _ to unused values with lexical-binding
From: |
Helmut Eller |
Subject: |
bug#8711: 24.0.50; binding _ to unused values with lexical-binding |
Date: |
Mon, 23 May 2011 22:32:56 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) |
* Stefan Monnier [2011-05-23 19:29] writes:
> I think the same problem happens with dotimes/dolist using the old
> definition: the loop vars `key' and `value' are let-bound outside the
> loop and then setq'd at each loop iteration (it's this setq that causes
> them to be "not left unused"). This was OK for the dynamic scoping case
> because let-binding is significantly more costly than setq, but it is
> not right for the lexical scoping case where the cost of let is not
> higher than `setq' and where the semantic is actually then wrong:
> e.g. if you "collect (lambda () value)" the current code ends up
> returning a list of functions that all return the last `value', rather
> than a list of functions that each return one of the `values' in
> the alist.
BTW, is there a good reason why we can't disallow setq on closed over
variables in Elisp? That kind of mutability seems like a bad idea in a
concurrent world. Closures are a new feature so we could make a
conscious decision not to introduce the problematic mutable variables.
Helmut
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Helmut Eller, 2011/05/21
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Lawrence Mitchell, 2011/05/23
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Stefan Monnier, 2011/05/23
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Helmut Eller, 2011/05/23
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Stefan Monnier, 2011/05/23
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Helmut Eller, 2011/05/23
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Stefan Monnier, 2011/05/23
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Helmut Eller, 2011/05/24
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Stefan Monnier, 2011/05/24
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding,
Helmut Eller <=
- bug#8711: 24.0.50; binding _ to unused values with lexical-binding, Stefan Monnier, 2011/05/23