just some syntactic nitpicking:
If I want to perform a map operation using a function…
def somefunc(x)
end
I have to do this:
l = [1,2,3].map { |x| somefunc x }
Why shouldnt I be able to do this:
l = [1,2,3].map somefunc
–SegPhault
Consider this:
$ irb
irb(main):001:0> def doubler(x); x * 2 end
=> nil
irb(main):002:0> (1…3).map &method(:doubler)
=> [2, 4, 6]
irb(main):003:0>
Cheers,
Kent.
On May 23, 2004, at 10:33 PM, Ryan Paul wrote:
just some syntactic nitpicking:
If I want to perform a map operation using a function…
def somefunc(x)
… perform some operation on x …
… and return a value …
end
I have to do this:
l = [1,2,3].map { |x| somefunc x }
Why shouldnt I be able to do this:
l = [1,2,3].map somefunc
–SegPhault
SegPhault wrote:
just some syntactic nitpicking:
If I want to perform a map operation using a function…
def somefunc(x)
… perform some operation on x …
… and return a value …
end
I have to do this:
l = [1,2,3].map { |x| somefunc x }
Why shouldn’t I be able to do this:
l = [1,2,3].map somefunc
It’s just not how Ruby works, for a number of reasons. If ‘somefunc’ were
truly a function, then it would seem strange not to be able to do that.
But ‘somefunc’ is a method, and as such it is bound up in the state of
some object.
Ruby will not sacrifice the purity of its OO concept for a bit of extra
convenience. (It already has convenience in spades.)
The ‘extensions’ project on RubyForge has a couple of shortcuts aimed at
map, but not in the (function-oriented) way you want.
require ‘extensions’
a = [1, -2, 3]
a.mapf :abs # short for a.map { |n| n.abs }
a.map &:abs # ditto
The second example is a bit ugly and opaque, but it can be applied to any
method, whereas the first is obviously limited to map/collect.
An alternative for your code is
a.map method(:somefunc)
Ultimately, you have to look at your suggested code
a.map somefunc
and realise that ‘somefunc’ must be either a local variable or a method
invocation. Treating it as a method object (like method(:somefunc)) would
mean that all method invocations would require parentheses, which would be
unpopular.
Cheers,
Gavin
Hi –
On Mon, 24 May 2004, Ryan Paul wrote:
just some syntactic nitpicking:
If I want to perform a map operation using a function…
def somefunc(x)
… perform some operation on x …
… and return a value …
end
I have to do this:
l = [1,2,3].map { |x| somefunc x }
Why shouldnt I be able to do this:
l = [1,2,3].map somefunc
Assuming you mean:
[1,2,3].map(:somefunc) # it would have to be a symbol or string
it’s been proposed as an RCR and rejected
(RCRS)
David
–
David A. Black
dblack@wobblini.net
I appreciate the good responses I get here. Another syntactic question:
why do we not have an ‘in’ operator like python does?
Ryan Paul wrote:
I appreciate the good responses I get here. Another syntactic question:
why do we not have an ‘in’ operator like python does?
David Black is going to think I paid you to ask that. 
I created RCR #241 for this, as I’ve been wanting it for over three
years. See http://rcrchive.net
I believe it could be added to the language easily and would represent
a minor improvement (which those who don’t like need not use).
Interestingly, there seems to be a wider spread of opinion on this
RCR than any other I have noticed. Some love it, some hate it, some
are neutral.
Cheers,
Hal
Ryan Paul segphault@sbcglobal.net writes:
I appreciate the good responses I get here. Another syntactic question:
why do we not have an ‘in’ operator like python does?
Would include? do what you want? e.g.
if legal_values.include? input_value then
…
end
Mike
–
mike@stok.co.uk | The “`Stok’ disclaimers” apply.
http://www.stok.co.uk/~mike/ | GPG PGP Key 1024D/059913DA
> Fingerprint 0570 71CD 6790 7C28 3D60
> 75D2 9EC4 C1C0 0599 13DA
I gave it my vote. It’s clear and its intuitive, whats not to love? I’m
surprised that it hasnt been implemented yet!
On Tue, 25 May 2004 02:12:15 +0900, Hal Fulton wrote:
Ryan Paul wrote:
I appreciate the good responses I get here. Another syntactic question:
why do we not have an ‘in’ operator like python does?
David Black is going to think I paid you to ask that.
I created RCR #241 for this, as I’ve been wanting it for over three
years. See http://rcrchive.netI believe it could be added to the language easily and would represent
a minor improvement (which those who don’t like need not use).Interestingly, there seems to be a wider spread of opinion on this
RCR than any other I have noticed. Some love it, some hate it, some
are neutral.Cheers,
Hal
“Mike Stok” mike@ratdog.stok.co.uk schrieb im Newsbeitrag
news:m2k6yxgzwt.fsf@ratdog.stok.co.uk…
Ryan Paul segphault@sbcglobal.net writes:
I appreciate the good responses I get here. Another syntactic
question:why do we not have an ‘in’ operator like python does?
Would include? do what you want? e.g.
if legal_values.include? input_value then
…
end
There’s already an RCR:
http://rcrchive.net/rcr/RCR/RCR241
robert