* Programmatic let
@ 2012-12-05 20:28 Lluís
2012-12-05 20:37 ` Grégoire Jadi
2012-12-05 20:39 ` Burton Samograd
0 siblings, 2 replies; 4+ messages in thread
From: Lluís @ 2012-12-05 20:28 UTC (permalink / raw)
To: emacs-devel
My elisp foo is quite poor, so this might well be a completely stupid approach
to the problem.
I have a callback that gets automatically called, and uses some orgmode-specific
routines whose behaviour can be tuned through some customizable variables.
The usual approach in orgmode is:
(let ((org-v1 ...) (org-v2 ...)) (org-func ...))
As my function is automatically called (as a response to the D-Bus message), I'd
like to let the user specify a let-like form to let her temporarily override the
behaviour of the `org-func' that my package invokes:
(setq my-cb-org-vars '((org-v1 ...) (org-v2 ...)))
(defun my-cb (...)
(programmatic-let my-cb-org-vars
(org-func ...)))
Is it possible to implement `programmatic-let'? And if so, can you throw me a
pointer to the appropriate docs?
Thanks,
Lluis
--
"And it's much the same thing with knowledge, for whenever you learn
something new, the whole world becomes that much richer."
-- The Princess of Pure Reason, as told by Norton Juster in The Phantom
Tollbooth
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Programmatic let
2012-12-05 20:28 Programmatic let Lluís
@ 2012-12-05 20:37 ` Grégoire Jadi
2012-12-05 20:48 ` Lluís
2012-12-05 20:39 ` Burton Samograd
1 sibling, 1 reply; 4+ messages in thread
From: Grégoire Jadi @ 2012-12-05 20:37 UTC (permalink / raw)
To: emacs-devel
[-- Attachment #1: Type: text/plain, Size: 1640 bytes --]
Lluís <xscript@gmx.net> writes:
> My elisp foo is quite poor, so this might well be a completely stupid approach
> to the problem.
>
> I have a callback that gets automatically called, and uses some orgmode-specific
> routines whose behaviour can be tuned through some customizable variables.
>
> The usual approach in orgmode is:
>
> (let ((org-v1 ...) (org-v2 ...)) (org-func ...))
>
> As my function is automatically called (as a response to the D-Bus message), I'd
> like to let the user specify a let-like form to let her temporarily override the
> behaviour of the `org-func' that my package invokes:
>
> (setq my-cb-org-vars '((org-v1 ...) (org-v2 ...)))
> (defun my-cb (...)
> (programmatic-let my-cb-org-vars
> (org-func ...)))
>
> Is it possible to implement `programmatic-let'? And if so, can you throw me a
> pointer to the appropriate docs?
You could use progv:
> (progv SYMBOLS VALUES &rest BODY)
>
> Bind SYMBOLS to VALUES dynamically in BODY.
> The forms SYMBOLS and VALUES are evaluated, and must evaluate to lists.
> Each symbol in the first list is bound to the corresponding value in the
> second list (or to nil if VALUES is shorter than SYMBOLS); then the
> BODY forms are executed and their result is returned. This is much like
> a `let' form, except that the list of symbols can be computed at run-time.
However, given a defined set of variables, you could parse
my-cb-org-vars yourself:
(defvar my-cb-org-vars '((x ...) (y ...)))
(defun my-cb (...)
(let ((x (cdr (assoc 'x my-cb-org-vars)))
(y (cdr (assoc 'y my-cb-org-vars))))
....))
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Programmatic let
2012-12-05 20:28 Programmatic let Lluís
2012-12-05 20:37 ` Grégoire Jadi
@ 2012-12-05 20:39 ` Burton Samograd
1 sibling, 0 replies; 4+ messages in thread
From: Burton Samograd @ 2012-12-05 20:39 UTC (permalink / raw)
To: emacs-devel
Lluís <xscript@gmx.net> writes:
> My elisp foo is quite poor, so this might well be a completely stupid approach
> to the problem.
>
> I have a callback that gets automatically called, and uses some orgmode-specific
> routines whose behaviour can be tuned through some customizable variables.
>
> The usual approach in orgmode is:
>
> (let ((org-v1 ...) (org-v2 ...)) (org-func ...))
>
> As my function is automatically called (as a response to the D-Bus message), I'd
> like to let the user specify a let-like form to let her temporarily override the
> behaviour of the `org-func' that my package invokes:
>
> (setq my-cb-org-vars '((org-v1 ...) (org-v2 ...)))
> (defun my-cb (...)
> (programmatic-let my-cb-org-vars
> (org-func ...)))
This should work:
(defmacro programmatic-let (vars &rest body)
`(let ,vars
,@body))
--
Burton Samograd
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Programmatic let
2012-12-05 20:37 ` Grégoire Jadi
@ 2012-12-05 20:48 ` Lluís
0 siblings, 0 replies; 4+ messages in thread
From: Lluís @ 2012-12-05 20:48 UTC (permalink / raw)
To: Grégoire Jadi; +Cc: emacs-devel
Grégoire Jadi writes:
> Lluís <xscript@gmx.net> writes:
>> My elisp foo is quite poor, so this might well be a completely stupid approach
>> to the problem.
>>
>> I have a callback that gets automatically called, and uses some orgmode-specific
>> routines whose behaviour can be tuned through some customizable variables.
>>
>> The usual approach in orgmode is:
>>
>> (let ((org-v1 ...) (org-v2 ...)) (org-func ...))
>>
>> As my function is automatically called (as a response to the D-Bus message), I'd
>> like to let the user specify a let-like form to let her temporarily override the
>> behaviour of the `org-func' that my package invokes:
>>
>> (setq my-cb-org-vars '((org-v1 ...) (org-v2 ...)))
>> (defun my-cb (...)
>> (programmatic-let my-cb-org-vars
>> (org-func ...)))
>>
>> Is it possible to implement `programmatic-let'? And if so, can you throw me a
>> pointer to the appropriate docs?
> You could use progv:
>> (progv SYMBOLS VALUES &rest BODY)
>>
>> Bind SYMBOLS to VALUES dynamically in BODY.
>> The forms SYMBOLS and VALUES are evaluated, and must evaluate to lists.
>> Each symbol in the first list is bound to the corresponding value in the
>> second list (or to nil if VALUES is shorter than SYMBOLS); then the
>> BODY forms are executed and their result is returned. This is much like
>> a `let' form, except that the list of symbols can be computed at run-time.
> However, given a defined set of variables, you could parse
> my-cb-org-vars yourself:
> (defvar my-cb-org-vars '((x ...) (y ...)))
> (defun my-cb (...)
> (let ((x (cdr (assoc 'x my-cb-org-vars)))
> (y (cdr (assoc 'y my-cb-org-vars))))
> ....))
Thanks a lot, `progv' is exactly what I want, given that the list of vars is not
known a priori.
Lluis
--
"And it's much the same thing with knowledge, for whenever you learn
something new, the whole world becomes that much richer."
-- The Princess of Pure Reason, as told by Norton Juster in The Phantom
Tollbooth
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-12-05 20:28 Programmatic let Lluís
2012-12-05 20:37 ` Grégoire Jadi
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2012-12-05 20:39 ` Burton Samograd
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