Questions tagged [proc-object]
47 questions
6
votes
4 answers
Why can procs be invoked with === in ruby 1.9?
This article mentions 4 ways to invoke procs in ruby 1.9, and === is one of them. I don't understand why this would be done this way at all. Does it have any relationship to the normal meaning of === (asking if the two objects are the same…
John Bachir
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6
votes
2 answers
How do we copy singleton methods between different Ruby classes?
I am trying to define a class with methods, and a class lacking those methods, and then allowing an object of the latter class to 'learn' the methods from an instance of the former class.
This is my attempt (Ruby 1.9.2) - it breaks (at the line…
Anthony
- 61
- 1
5
votes
1 answer
Are there any "simple" explanations of what procs and lambdas are in Ruby?
Are there any "simple" explanations of what procs and lambdas are in Ruby?
yazz.com
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4
votes
2 answers
How do I using instance variables from within a lambda/Proc defined in a class variable?
I wrote the following code:
class Actions
def initialize
@people = []
@commands = {
"ADD" => ->(name){@people << name },
"REMOVE" => ->(n=0){ puts "Goodbye" },
"OTHER" => ->(n=0){puts "Do Nothing" }
}
end
def…
Srgrn
- 1,770
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4
votes
2 answers
Ruby Lambda vs. Proc LocalJumpError
Ruby and StackOverflow newb here working my way through Ruby and ran into my first major roadblock. I'm having a really hard time wrapping my head around Procs and Lambdas. Here is the code I'm working with.
def procBuilder(message)
Proc.new{ puts…
Tim Lindsey
- 727
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4
votes
2 answers
tcl: wrap a proc of the same name
I want to replace the definition of "proc N" with a proc of the same name and calling conventions, but with a little extra error detection code.
In python I could do what I want like below, but I don't have any grasp of how namespaces and function…
bukzor
- 37,539
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4
votes
3 answers
Trouble with setting attributes
I have an item ActiveRecords and I am trying to set a default value ("Test item") for each of them using a block.
In this expression:
list = {"type1", "type2", "type3", "type4", "..."}
list.each { |name| @item.attributes["#{name}"] = "Test item"]…
user502052
- 14,803
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4
votes
3 answers
How do I print out a tcl proc?
Given a simple tcl proc like
proc foo {a b} {puts "$a $b"}
What tcl command can I use to print out the procedure foo ... that is I want the text of the proc back ...
For instance:
% proc foo {a b} {puts "$a $b"}
% foo a b
a b
% puts $foo
…
Xofo
- 41
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3
votes
1 answer
What are the advantages of proc functions to methods
I was solving some problems on Project Euler and I mentioned that I always wrap short methods in proc functions. I asked myself "Why?". The answer was "I don't know. Maybe because it is short?".
So what are the advantages of proc functions to…
fl00r
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3
votes
3 answers
TCL - return variable vs upvar and modify
Would like to take an advice from TCL professionals for best practice.
Say you want to construct a list with a specific data by using a proc. Now which is the best way?
proc processList { myList } {
upvar $myList list_
#append necessary data…
Narek
- 38,779
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3
votes
2 answers
Proc.new in Ruby: when do I need to use it?
The date_validator in its examples has a comment:
Using Proc.new prevents production cache issues
Does it mean, that everywhere in my code, where I use current time related methods (Time.now, 1.day.since(Time.zone.now), etc.) I should surround them…
krn
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3
votes
1 answer
Referencing a local variable from a Proc defined in another scope
I want to create an instance method which varies its behaviour with return value of another method depending on a implementation of its overwrites in a polymorphic manner.
For example, the following class is assumed to be extended and pricing_rule…
suzukimilanpaak
- 751
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3
votes
1 answer
Behavior of 'return' keyword within a ruby block
Can someone explain the behavior of the following
def iterate
return yield
return "end of iterate"
end
def test_iterate
assert_equal( "end of iterate", iterate { return "end of block" } )
assert_equal( "end of block", iterate { "end of…
Derrick J Wippler
- 313
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- 7
3
votes
2 answers
Inconsistency of arity between Hash.each and lambdas
I lifted the following example from Josh Susser
def strip_accents params
thunk = lambda do |key,value|
case value
when String then value.remove_accents!
when Hash then value.each(&thunk)
end
end
…
SooDesuNe
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3
votes
1 answer
Are there Ruby precedence issues with using Proc.call vs. Proc.[]?
Recently I was having a discussion with a friend about Ruby's Proc. You can call a Proc in one of several ways. One way is to invoke Proc.call:
p = Proc.new { |x| "hello, #{x}" }
p.call "Bob"
=> "hello, Bob"
Another is to use braces, Proc.[]:
p…
John Feminella
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