Finding a function's expected argument list length
For some work I'm doing it would be very nice to be able to know the number of arguments any given function expects to be called with. Is there anyway to get this information at run-time in Clojure? Thanks. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Finding a function's expected argument list length
No. The summary is: from Java's point of view every function is willing to accept any number of args, but many of the implementations throw an exception. Vars have an :arglists metadata key, but that is not generally present on functions. I agree it would be nice if function objects carried a set of acceptable arities with them, but I haven't thought very hard about it - perhaps the performance implication this imposes on every function isn't worth it for the small minority of times when you need to ask the question. On Oct 20, 5:58 pm, Alex Baranosky alexander.barano...@gmail.com wrote: For some work I'm doing it would be very nice to be able to know the number of arguments any given function expects to be called with. Is there anyway to get this information at run-time in Clojure? Thanks. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Finding a function's expected argument list length
In a REPL,
user (defn hello [name]
(println hi, name))
#'user/hello
user (meta (var hello))
{:ns #Namespace user, :name hello, :file NO_SOURCE_FILE, :line 1,
:arglists ([name])}
Please also check - http://clojuredocs.org/clojure_core/clojure.core/meta
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Re: Finding a function's expected argument list length
I figured, but had to ask. I'm looking into adding a feature to Midje to be able to say: (defn g [a b c d e f g] nil) (fact (f 1) = 1 (provided (g ...) :never )) instead of what you currently have to say for the equivalent: (fact (f 1) = 1 (provided (g anything anything anything anything anything anything anything) = anything :never )) Knowing the arity of the function would have helped with the internals. On Thu, Oct 20, 2011 at 11:42 PM, Alan Malloy a...@malloys.org wrote: No. The summary is: from Java's point of view every function is willing to accept any number of args, but many of the implementations throw an exception. Vars have an :arglists metadata key, but that is not generally present on functions. I agree it would be nice if function objects carried a set of acceptable arities with them, but I haven't thought very hard about it - perhaps the performance implication this imposes on every function isn't worth it for the small minority of times when you need to ask the question. On Oct 20, 5:58 pm, Alex Baranosky alexander.barano...@gmail.com wrote: For some work I'm doing it would be very nice to be able to know the number of arguments any given function expects to be called with. Is there anyway to get this information at run-time in Clojure? Thanks. -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: Finding a function's expected argument list length
Thanks. I'm going to have to see if that could help with what I'm trying to
do.
On Thu, Oct 20, 2011 at 11:45 PM, mmwaikar mmwai...@gmail.com wrote:
In a REPL,
user (defn hello [name]
(println hi, name))
#'user/hello
user (meta (var hello))
{:ns #Namespace user, :name hello, :file NO_SOURCE_FILE, :line 1,
:arglists ([name])}
Please also check - http://clojuredocs.org/clojure_core/clojure.core/meta
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