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Questions tagged [parameter-passing]

parameter-passing is the process of assigning values to the parameters of a function

Association of actual and formal parameters upon function call. See Parameter Passing and its methods. The most widely used parameter passing methods are:

  • call-by-value
  • call-by-reference
  • call-by-value-result
  • call-by-name
  • call-by-need
  • macro expansion.
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Is Java "pass-by-reference" or "pass-by-value"?

I always thought Java uses pass-by-reference. However, I read a blog post which claims that Java uses pass-by-value. I don't think I understand the distinction the author is making. What is the explanation?
user4315
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What does ** (double star/asterisk) and * (star/asterisk) do for parameters?

What do *args and **kwargs mean in these function definitions? def foo(x, y, *args): pass def bar(x, y, **kwargs): pass See What do ** (double star/asterisk) and * (star/asterisk) mean in a function call? for the complementary question…
Todd
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How do I pass a variable by reference?

I wrote this class for testing: class PassByReference: def __init__(self): self.variable = 'Original' self.change(self.variable) print(self.variable) def change(self, var): var = 'Changed' When I tried…
David Sykes
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Check number of arguments passed to a Bash script

I would like my Bash script to print an error message if the required argument count is not met. I tried the following code: #!/bin/bash echo Script name: $0 echo $# arguments if [$# -ne 1]; then echo "illegal number of parameters" fi For…
triple fault
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How to pass all arguments passed to my Bash script to a function of mine?

Let's say I have a function abc() that will handle the logic related to analyzing the arguments passed to my script. How can I pass all arguments my Bash script has received to abc()? The number of arguments is variable, so I can't just hard-code…
devoured elysium
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What do ** (double star/asterisk) and * (star/asterisk) mean in a function call?

In code like zip(*x) or f(**k), what do the * and ** respectively mean? How does Python implement that behaviour, and what are the performance implications? See also: Expanding tuples into arguments. Please use that one to close questions where OP…
psihodelia
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How to write a bash script that takes optional input arguments?

I want my script to be able to take an optional input, e.g. currently my script is #!/bin/bash somecommand foo but I would like it to say: #!/bin/bash somecommand [ if $1 exists, $1, else, foo ]
Abe
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How can I pass an argument to a PowerShell script?

There's a PowerShell script named itunesForward.ps1 that makes iTunes fast forward 30 seconds: $iTunes = New-Object -ComObject iTunes.Application if ($iTunes.playerstate -eq 1) { $iTunes.PlayerPosition = $iTunes.PlayerPosition + 30 } It is…
Boris Pavlović
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How do I pass multiple parameters into a function in PowerShell?

If I have a function which accepts more than one string parameter, the first parameter seems to get all the data assigned to it, and remaining parameters are passed in as empty. A quick test script: Function Test([string]$arg1, [string]$arg2) { …
Nasir
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Expanding tuples into arguments

Suppose I have a function like: def myfun(a, b, c): return (a * 2, b + c, c + b) Given a tuple some_tuple = (1, "foo", "bar"), how would I use some_tuple to call myfun? This should output the result (2, "foobar", "barfoo"). I know could define…
AkiRoss
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What does map(&:name) mean in Ruby?

I found this code in a RailsCast: def tag_names @tag_names || tags.map(&:name).join(' ') end What does the (&:name) in map(&:name) mean?
collimarco
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How to pass a function as a parameter in Java?

In Java, how can one pass a function as an argument to another function?
Jason
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What does a bare asterisk do in a Python parameter list? (What are "keyword-only" parameters?)

What does a bare asterisk in the parameters of a function do? When I looked at the pickle module, I see this: pickle.dump(obj, file, protocol=None, *, fix_imports=True) I know about a single and double asterisks preceding parameters (for variable…
Eric
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JavaScript: Passing parameters to a callback function

I'm trying to pass some parameter to a function used as callback, how can I do that? This is my try: function tryMe(param1, param2) { alert(param1 + " and " + param2); } function callbackTester(callback, param1, param2) { callback(param1,…
vitto
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Why use the params keyword?

I know this is a basic question, but I couldn't find an answer. Why use it? if you write a function or a method that's using it, when you remove it the code will still work perfectly, 100% as without it. E.g: With params: static public int…
MasterMastic
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