Re: Invoke a specific multimethod
Just copy/paste from my Counterclockwise REPL. :-)
- Chas
On Mar 30, 2013, at 11:54 PM, JvJ wrote:
Also, nice syntax highlighting! How'd you do that?
On Saturday, 30 March 2013 23:54:03 UTC-4, JvJ wrote:
get-method. Thanks, that was exactly what I was looking for!
On Saturday, 30 March 2013 07:20:54 UTC-4, Chas Emerick wrote:
On Mar 30, 2013, at 12:00 AM, George Oliver wrote:
On Friday, March 29, 2013 6:19:19 PM UTC-7, JvJ wrote:
Is it possible to invoke a particular multimethod and bypass the dispatch
function?
For instance, suppose that I have a multimethod with a dispatch value of
::foo, and it's a really complex method.
Now, I want all cases where the dispatch function returns nil to use the
same multimethod. Is there a way I can intercept the nil and
pass it directly on to the ::foo multimethod?
You could use the default multimethod to catch nil, and then call the multi
with ::foo.
That will only work if the dispatch fn is identity or similar.
If you control the dispatch fn, then you don't need to intercept nil --
just returning ::foo from the dispatch fn when it might otherwise return nil
will get you to the method you want.
If you *don't* control the dispatch fn, but you're providing the methods for
:foo and nil, then you can use `get-method` to obtain the method associated
with a particular dispatch value:
= (defmulti foo :bar)
#'user/foo
= (defmethod foo :baz
[x]
(str x))
#MultiFn clojure.lang.MultiFn@6194a872
= (defmethod foo :default
[x]
((get-method foo :baz) x))
#MultiFn clojure.lang.MultiFn@6194a872
= (foo {:bar :baz})
{:bar :baz}
= (foo {:some :other :value :here})
{:some :other, :value :here}
Of course, if the functionality you need is available as a separate top-level
fn, and you can avoid the extra effective dispatch through the multimethod,
all the better.
Cheers,
- Chas
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Re: Invoke a specific multimethod
On Mar 30, 2013, at 12:00 AM, George Oliver wrote:
On Friday, March 29, 2013 6:19:19 PM UTC-7, JvJ wrote:
Is it possible to invoke a particular multimethod and bypass the dispatch
function?
For instance, suppose that I have a multimethod with a dispatch value of
::foo, and it's a really complex method.
Now, I want all cases where the dispatch function returns nil to use the same
multimethod. Is there a way I can intercept the nil and
pass it directly on to the ::foo multimethod?
You could use the default multimethod to catch nil, and then call the multi
with ::foo.
That will only work if the dispatch fn is identity or similar.
If you control the dispatch fn, then you don't need to intercept nil -- just
returning ::foo from the dispatch fn when it might otherwise return nil will
get you to the method you want.
If you *don't* control the dispatch fn, but you're providing the methods for
:foo and nil, then you can use `get-method` to obtain the method associated
with a particular dispatch value:
= (defmulti foo :bar)
#'user/foo
= (defmethod foo :baz
[x]
(str x))
#MultiFn clojure.lang.MultiFn@6194a872
= (defmethod foo :default
[x]
((get-method foo :baz) x))
#MultiFn clojure.lang.MultiFn@6194a872
= (foo {:bar :baz})
{:bar :baz}
= (foo {:some :other :value :here})
{:some :other, :value :here}
Of course, if the functionality you need is available as a separate top-level
fn, and you can avoid the extra effective dispatch through the multimethod, all
the better.
Cheers,
- Chas
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Re: Invoke a specific multimethod
get-method. Thanks, that was exactly what I was looking for!
On Saturday, 30 March 2013 07:20:54 UTC-4, Chas Emerick wrote:
On Mar 30, 2013, at 12:00 AM, George Oliver wrote:
On Friday, March 29, 2013 6:19:19 PM UTC-7, JvJ wrote:
Is it possible to invoke a particular multimethod and bypass the dispatch
function?
For instance, suppose that I have a multimethod with a dispatch value of
::foo, and it's a really complex method.
Now, I want all cases where the dispatch function returns nil to use the
same multimethod. Is there a way I can intercept the nil and
pass it directly on to the ::foo multimethod?
You could use the default multimethod to catch nil, and then call the
multi with ::foo.
That will only work if the dispatch fn is identity or similar.
If you control the dispatch fn, then you don't need to intercept nil --
just returning ::foo from the dispatch fn when it might otherwise return
nil will get you to the method you want.
If you *don't* control the dispatch fn, but you're providing the methods
for :foo and nil, then you can use `get-method` to obtain the method
associated with a particular dispatch value:
= (*defmulti* foo :bar)
#'user/foo
= (*defmethod* foo :baz
[x]
(str x))
#MultiFn clojure.lang.MultiFn@6194a872
= (*defmethod* foo :default
[x]
((get-method foo :baz) x))
#MultiFn clojure.lang.MultiFn@6194a872
= (foo {:bar :baz})
{:bar :baz}
= (foo {:some :other :value :here})
{:some :other, :value :here}
Of course, if the functionality you need is available as a separate
top-level fn, and you can avoid the extra effective dispatch through the
multimethod, all the better.
Cheers,
- Chas
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Re: Invoke a specific multimethod
Also, nice syntax highlighting! How'd you do that?
On Saturday, 30 March 2013 23:54:03 UTC-4, JvJ wrote:
get-method. Thanks, that was exactly what I was looking for!
On Saturday, 30 March 2013 07:20:54 UTC-4, Chas Emerick wrote:
On Mar 30, 2013, at 12:00 AM, George Oliver wrote:
On Friday, March 29, 2013 6:19:19 PM UTC-7, JvJ wrote:
Is it possible to invoke a particular multimethod and bypass the
dispatch function?
For instance, suppose that I have a multimethod with a dispatch value of
::foo, and it's a really complex method.
Now, I want all cases where the dispatch function returns nil to use the
same multimethod. Is there a way I can intercept the nil and
pass it directly on to the ::foo multimethod?
You could use the default multimethod to catch nil, and then call the
multi with ::foo.
That will only work if the dispatch fn is identity or similar.
If you control the dispatch fn, then you don't need to intercept nil --
just returning ::foo from the dispatch fn when it might otherwise return
nil will get you to the method you want.
If you *don't* control the dispatch fn, but you're providing the methods
for :foo and nil, then you can use `get-method` to obtain the method
associated with a particular dispatch value:
= (*defmulti* foo :bar)
#'user/foo
= (*defmethod* foo :baz
[x]
(str x))
#MultiFn clojure.lang.MultiFn@6194a872
= (*defmethod* foo :default
[x]
((get-method foo :baz) x))
#MultiFn clojure.lang.MultiFn@6194a872
= (foo {:bar :baz})
{:bar :baz}
= (foo {:some :other :value :here})
{:some :other, :value :here}
Of course, if the functionality you need is available as a separate
top-level fn, and you can avoid the extra effective dispatch through the
multimethod, all the better.
Cheers,
- Chas
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Invoke a specific multimethod
Is it possible to invoke a particular multimethod and bypass the dispatch function? For instance, suppose that I have a multimethod with a dispatch value of ::foo, and it's a really complex method. Now, I want all cases where the dispatch function returns nil to use the same multimethod. Is there a way I can intercept the nil and pass it directly on to the ::foo multimethod? -- -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: Invoke a specific multimethod
On Friday, March 29, 2013 6:19:19 PM UTC-7, JvJ wrote: Is it possible to invoke a particular multimethod and bypass the dispatch function? For instance, suppose that I have a multimethod with a dispatch value of ::foo, and it's a really complex method. Now, I want all cases where the dispatch function returns nil to use the same multimethod. Is there a way I can intercept the nil and pass it directly on to the ::foo multimethod? You could use the default multimethod to catch nil, and then call the multi with ::foo. -- -- 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 unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
