Re: exit trap inside ksh-style function in bash-2.05b

[Chet Ramey]

> (1)
> 
> (function t { trap 'printf "%s" a' exit; }; t; printf "%s" b)
> => ba
> 
> Per ksh man page:
> 
> A trap on EXIT set inside a [ksh-style] function is executed in
> the environment of the caller after the function completes.
> 
> Also Bolsky and Korn, page 162.
> 
> Since bash adopted the ksh-style function, it should follow its
> documentation. I see no good reason to be different.

Bash has not `adopted the ksh-style function'.  Bash functions conform
to POSIX.2, regardless of the syntax used to declare them.

POSIX.2 requires that shell functions share the calling shell's
environment, which includes traps.

> As a supporting evidence, "zsh version 3.0" that I happen to have
> (I am not a zsh user) behaves the same as the correct implementation
> of ksh. That is, (1) produces "ab" and $z in (2) is "ab".

How is this `supporting evidence'?  Bash isn't ksh, and it's not zsh,
either.

Now, that said, bash-3.0 includes a `RETURN' trap, which is executed when
a shell function or sourced script returns.  It was implemented as part
of the bash debugger support.

Chet

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
( ``Discere est Dolere'' -- chet )
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Chet Ramey, ITS, CWRU    chet@po.cwru.edu    http://tiswww.tis.cwru.edu/~chet/