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Subject: |
29.0.50; Improve behavior of conditionals in Eshell |
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Date: |
Wed, 10 Aug 2022 19:43:22 -0700 |
In Eshell, you can use conditionals pretty much like you'd expect from
other shells. Starting from 'emacs -Q -f eshell':
~ $ [ foo = foo ] && echo hi
hi
~ $ [ foo = bar ] && echo hi
~ $ [ foo = foo ] || echo hi
~ $ [ foo = bar ] || echo hi
hi
~ $ if {[ foo = foo ]} {echo yes} {echo no}
yes
~ $ if {[ foo = bar ]} {echo yes} {echo no}
no
However, that only works for external commands. If the command is
implemented in Lisp, it doesn't work:
~ $ (zerop 0) && echo hi
t
hi
~ $ (zerop 1) && echo hi
hi ;; Shouldn't say hi.
That's because the exit status is always 0 for Lisp commands. This works
correctly for external commands:
~ $ [ foo = foo ]; echo status $? result $$
("status" 0 "result" nil)
~ $ [ foo = bar ]; echo status $? result $$
("status" 1 "result" nil)
But not for Lisp commands:
~ $ (zerop 0); echo status $? result $$
t
("status" 0 "result" t)
~ $ (zerop 1); echo status $? result $$
("status" 0 "result" nil)
~ $ (zerop "foo"); echo status $? result $$
Wrong type argument: number-or-marker-p, "foo"
("status" 0 "result" nil)
The manual says that the status should be 1 when a Lisp command fails,
but it's 0 no matter what, even if it signaled an error. (Likewise, the
manual says that the "result" variable should be t for successful
external commands, but it's always nil.)
Similarly to the above, you can't use variable expansions for conditionals:
~ $ (setq foo t)
t
~ $ if $foo {echo yes} {echo no}
yes
~ $ (setq foo nil)
~ $ if $foo {echo yes} {echo no}
yes ;; Should say no.
Patch forthcoming. Just splitting it into two messages since it seemed
more readable that way...
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--- Begin Message ---
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Subject: |
Re: bug#57129: 29.0.50; Improve behavior of conditionals in Eshell |
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Date: |
Wed, 15 Mar 2023 22:35:24 -0700 |
On 8/25/2022 10:10 PM, Jim Porter wrote:
On 8/24/2022 2:41 PM, Jim Porter wrote:
On 8/20/2022 11:03 AM, Jim Porter wrote:
In addition to the changes to temporary file name generation, I think
it would be useful for Eshell to kill the temporary buffer too.
[snip]
Attached is a patch to do this.
Assuming there are no remaining objections, I'll merge this in a day
or two.
Merged as a457aa62577284333c7d25d48a49704788b25a04.
I know there was a quite-lengthy discussion about the tempname function,
but I think those patches were merged, along with my patch for the
original bug topic. Therefore, I'm going to close this.
Of course, if there's still anything to do with the tempname stuff,
let's do it (though it might help to give it a separate bug for tracking
purposes).
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