to_i vs. to_int

[Ico]

Hello,

I have a class which instances can be represented as integers. What is
the difference between the to_i and to_int methods, and when is which
form needed ?

Ico

 

[gabriele renzi]

Ico ha scritto:

Hello,

I have a class which instances can be represented as integers. What is
the difference between the to_i and to_int methods, and when is which
form needed ?

short names (to_x) are for common programmer use.
Long names (to_xyz) are there so that ruby can do some implicit
conversions between things that can basically be threated as xyz.

So in your case it could be meaningful to define one and alias the other
to it.

 

[dblack]

Hi --

Ico ha scritto:

short names (to_x) are for common programmer use.
Long names (to_xyz) are there so that ruby can do some implicit conversions
between things that can basically be threated as xyz.

So in your case it could be meaningful to define one and alias the other to
it.

What's a use case for to_int? I was thinking of this classic to_str
example:

class S
def to_str
"some text"
end
end

puts "Here is " + S.new # Here is some text

But the to_int equivalent doesn't work:

class S
def to_int
2
end
end

puts 2 + S.new # TypeError: S can't be coerced into Fixnum

Same thing with:

puts Integer(2) + S.new

I'm stuck trying to find a case where to_int does what to_str does --
but maybe it doesn't.


David

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[ts]

d> class S
d> def to_int
d> 2
d> end
d> end

d> puts 2 + S.new # TypeError: S can't be coerced into Fixnum

puts 2 | S.new


Guy Decoux

 

[dblack]

Hi --

d> class S
d> def to_int
d> 2
d> end
d> end

d> puts 2 + S.new # TypeError: S can't be coerced into Fixnum

puts 2 | S.new

Interesting. What's the rationale for not doing the conversion for +
and - and other operator/methods?


David

--
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----> SEE SPECIAL DEAL FOR RUBY/RAILS USERS GROUPS! <-----
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http://www.manning.com/black => book, Ruby for Rails
http://www.rubycentral.org => Ruby Central, Inc.

 

[Morton Goldberg]

What's a use case for to_int? I was thinking of this classic to_str
example:

class S
def to_str
"some text"
end
end

puts "Here is " + S.new # Here is some text

But the to_int equivalent doesn't work:

class S
def to_int
2
end
end

puts 2 + S.new # TypeError: S can't be coerced into Fixnum

Same thing with:

puts Integer(2) + S.new

I'm stuck trying to find a case where to_int does what to_str does --
but maybe it doesn't.

However,

puts 2 + Integer(S.new) => 4

uses your S#to_int

Regards, Morton

 

[dblack]

Hi --

However,

puts 2 + Integer(S.new) => 4

uses your S#to_int

True, but it works the same with to_i, as opposed to the string one
where to_s and to_str work differently.


David

--
http://www.rubypowerandlight.com => Ruby/Rails training & consultancy
----> SEE SPECIAL DEAL FOR RUBY/RAILS USERS GROUPS! <-----
http://dablog.rubypal.com => D[avid ]A[. ]B[lack's][ Web]log
http://www.manning.com/black => book, Ruby for Rails
http://www.rubycentral.org => Ruby Central, Inc.

 

[gabriele renzi]

(e-mail address removed) ha scritto:

Hi --

also, Arrays seem to like it:

a=Object.new

def a.to_int() 2 end => nil
[0,1,3][a] => 3
Array.new(a){ 0 }

=> [0, 0]

Interesting. What's the rationale for not doing the conversion for +
and - and other operator/methods?

I'd like to know the same

 

[Aleks Kissinger]

We actually gabbed on this topic a bit recently. See the second half
of the "Symbols are your friends" thread from a couple of days ago.

(e-mail address removed) ha scritto:

Hi --

also, Arrays seem to like it:

a=Object.new

def a.to_int() 2 end => nil
[0,1,3][a] => 3
Array.new(a){ 0 }

=> [0, 0]

Interesting. What's the rationale for not doing the conversion for +
and - and other operator/methods?

I'd like to know the same

 

[gabriele renzi]

Aleks Kissinger ha scritto:

We actually gabbed on this topic a bit recently. See the second half
of the "Symbols are your friends" thread from a couple of days ago.

Oh, I missed this, thank you