10:35 a.m.
There's a function I wanted in the context of svm() -- to get all the
keys from a bundle in the form of an array of strings -- and I thought
it might be useful to have it exposed in hansl under the name getkeys.
Could be helpful for function writers, if you're taking in a bunch of
arguments in the form of bundle elements, some of them optional.
The idea is that you can check for mistyping of parameter names, and
hence maybe save a user some puzzlement ("I set X but it didn't have
any effect!").
Trivial illustration follows.
<hansl>
function scalar in_strings_array (const strings S, const string s)
scalar ok = 0
loop i=1..nelem(S) -q
if s == S[i]
ok = 1
break
endif
endloop
return ok
end function
function void do_something (const bundle parms)
strings ok_keys = defarray("foo", "bar", "baz")
strings pnames = getkeys(parms)
loop i=1..nelem(pnames) -q
if !in_strings_array(ok_keys, pnames[i])
errstr = sprintf("Unrecognized parameter '%s'", pnames[i])
funcerr errstr
endif
endloop
end function
bundle b = defbundle("foo", 3, "bar", "some text",
"bax", I(2))
do_something(b)
</hansl>
Here, do_something() accepts a bundled parameter "baz" (implicitly
optional) which has been mistyped as "bax". Instead of "bax" being
silently ignored the result is:
Error message from do_something():
Unrecognized parameter 'bax'
I guess the example invites the idea that inarray() could be a
built-in function for arrays of strings (at least). Any thoughts on
whether that would be worthwhile?
Allin
3:52 p.m.
Am 04.03.2018 um 16:35 schrieb Allin Cottrell:
There's a function I wanted in the context of svm() -- to get all
the
keys from a bundle in the form of an array of strings -- and I thought
it might be useful to have it exposed in hansl under the name getkeys.
Thanks, sounds useful!
I guess the example invites the idea that inarray() could be a
built-in
function for arrays of strings (at least). Any thoughts on whether that
would be worthwhile?
In principle, yes. However, maybe it's worth pointing out that if we had
a function to stuff all the array elements together (say, 'concat'),
then it would just be a matter of doing:
strstr(concat(mystrings), "findme")
(Where in my imagination 'concat' would also work on other array types:
matrices and bundles.)
cheers,
sven
7:57 p.m.
On Sun, 4 Mar 2018, Sven Schreiber wrote:
Am 04.03.2018 um 16:35 schrieb Allin Cottrell:
> There's a function I wanted in the context of svm() -- to get all the keys
> from a bundle in the form of an array of strings -- and I thought it might
> be useful to have it exposed in hansl under the name getkeys.
Thanks, sounds useful!
> I guess the example invites the idea that inarray() could be a built-in
> function for arrays of strings (at least). Any thoughts on whether that
> would be worthwhile?
In principle, yes. However, maybe it's worth pointing out that if we had a
function to stuff all the array elements together (say, 'concat'), then it
would just be a matter of doing:
strstr(concat(mystrings), "findme")
What if the array contained an element "findmeNOT", but no element
"findme"?
Allin
3:52 a.m.
Am 05.03.2018 um 01:57 schrieb Allin Cottrell:
On Sun, 4 Mar 2018, Sven Schreiber wrote:
> In principle, yes. However, maybe it's worth pointing out
that if we
> had a function to stuff all the array elements together (say,
> 'concat'), then it would just be a matter of doing:
>
> strstr(concat(mystrings), "findme")
What if the array contained an element "findmeNOT", but no element
"findme"?
Good point. In analogy to 'strsplit' the function 'concat' could anyway
use a second optional argument that specifies a joining character. Then
it would be possible to do:
strstr(concat(mystrings, ","), ",findme,")
At least that would cover the problem of searching bundle keys because
commas are not allowed there. But of course it wouldn't be a general
equivalent to an inarray function. And I admit it's much less attractive.
thanks,
sven
1:43 a.m.
On 04.03.2018 16:35, Allin Cottrell wrote:
There's a function I wanted in the context of svm() -- to get all
the
keys from a bundle in the form of an array of strings -- and I thought
it might be useful to have it exposed in hansl under the name getkeys.
Could be helpful for function writers, if you're taking in a bunch of
arguments in the form of bundle elements, some of them optional.
The idea is that you can check for mistyping of parameter names, and
hence maybe save a user some puzzlement ("I set X but it didn't have
any effect!").
Trivial illustration follows.
<hansl>
function scalar in_strings_array (const strings S, const string s)
scalar ok = 0
loop i=1..nelem(S) -q
if s == S[i]
ok = 1
break
endif
endloop
return ok
end function
function void do_something (const bundle parms)
strings ok_keys = defarray("foo", "bar", "baz")
strings pnames = getkeys(parms)
loop i=1..nelem(pnames) -q
if !in_strings_array(ok_keys, pnames[i])
errstr = sprintf("Unrecognized parameter '%s'", pnames[i])
funcerr errstr
endif
endloop
end function
bundle b = defbundle("foo", 3, "bar", "some text",
"bax", I(2))
do_something(b)
</hansl>
Here, do_something() accepts a bundled parameter "baz" (implicitly
optional) which has been mistyped as "bax". Instead of "bax" being
silently ignored the result is:
Error message from do_something():
Unrecognized parameter 'bax'
I guess the example invites the idea that inarray() could be a
built-in function for arrays of strings (at least). Any thoughts on
whether that would be worthwhile?
Allin
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Very useful for me.
Regards,
Marcin
--
Marcin Błażejowski
2449
days inactive
2450
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4 comments
3 participants
participants (3)
-
Allin Cottrell -
Marcin Błażejowski -
Sven Schreiber