An optional argument is an argument which can be omitted, eventually being replaced by a default value, where an argument is an actual value passed to a function, procedure, or command line program.
Questions tagged [optional-arguments]
223 questions
17
votes
3 answers
Optional argument cannot be erased?
I wanted to have a tail-recursive version of List.map, so I wrote my own. Here it is:
let rec list_map f l ?(accum=[])=
match l with
head :: tail -> list_map f tail ~accum:(head :: accum)
| [] -> accum;;
Whenever I compile this…
Jason Baker
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15
votes
2 answers
Multiple optional arguments python
So I have a function with several optional arguments like so:
def func1(arg1, arg2, optarg1=None, optarg2=None, optarg3=None):
Optarg1 & optarg2 are usually used together and if these 2 args are specified then optarg3 is not used. By contrast, if…
e9e9s
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14
votes
3 answers
Generic methods and optional arguments
Is it possible to write similar construction?
I want to set, somehow, default value for argument of type T.
private T GetNumericVal(string sColName, T defVal = 0)
{
string sVal = GetStrVal(sColName);
T nRes;
if…
hardsky
- 514
- 5
- 15
13
votes
3 answers
Propagating optional arguments
The following code does not compile.
type A(?arg) =
member __.Arg : string option = arg
type B(?arg) =
inherit A(arg) //ERROR expected type string but has type 'a option
I assume this is because an instance of the underlying type of the option…
Daniel
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13
votes
4 answers
How to write a test for a function with optional arguments
I want to test function calls with optional arguments.
Here is my code:
list_get()
list_get(key, "city", 0)
list_get(key, 'contact_no', 2, {}, policy)
list_get(key, "contact_no", 0)
list_get(key, "contact_no", 1, {}, policy, "")
list_get(key,…
Pavan Gupta
- 17,663
- 4
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- 29
12
votes
1 answer
Map Update method with ifAbsent in Dart
I'd like to modify an existing item in a map, as in replace the value of an existing key with a new one, with an added clause if the key does not exist in the Map already, to simply create a new key and value pair. The Dart documentation suggests…
Terrornado
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11
votes
5 answers
Function with dictionaries as optional arguments - Python
I'm trying to create a function that might receive as input many or a few dictionaries. I'm using the following code:
def merge_many_dics(dic1,dic2,dic3=True,dic4=True,dic5=True,dic6=True,dic7=True,dic8=True,dic9=True,dic10=True):
"""
Merging up to…
aabujamra
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10
votes
2 answers
Why default arguments in F# (FSharpOption) are reference types?
C# and F# has different implementation of the default (or optional) parameters.
In C# language when you add default value to the argument you'll not change its underlying type (I mean type of the parameter). Actually optional arguments in C# is a…
Sergey Teplyakov
- 11,477
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- 49
9
votes
2 answers
Python 3.5 TypeError: got multiple values for argument
def f(a, b, *args):
return (a, b, args)
f(a=3, b=5)
(3, 5, ())
whereas:
f(a=3, b=5, *[1,2,3])
TypeError: got multiple values for argument 'b'
Why it behaves like this?
Any particular reason?
Jan Sikora
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9
votes
1 answer
Is it necessary to check an optional argument before passing it to another optional argument?
I have the following question concerning the usage of optional argument. Let's say I have the following routine aaa defined in module m_aaa
MODULE m_aaa
SUBROUTINE aaa(a, b)
INTEGER :: a
INTEGER, OPTIONAL :: b
END SUBROUTINE
END…
Leos Mervart
- 93
- 3
9
votes
3 answers
Optional arguments with default value in Ruby
I would like to create a function that has optional arguments with default values
def my_function(a = nil, b=nil, c=500)
end
and call the function with the arguments I would like to specify only
my_function(b=100)
How do I accomplish this in Ruby…
AdamNYC
- 19,887
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8
votes
6 answers
Assign pass to a function in Python
I have a piece of code that defines a function that takes a function as an argument, like so:
def stuff(n, f):
f(n)
Now, I want to provide some default value of f that does nothing. So I figured I'd use pass, like so:
def stuff(n, f = None):
…
LinuxMercedes
- 251
- 5
- 10
8
votes
2 answers
Matlab - Optional handle argument first for plot like functions
Matlab includes many plotting functions which take an optional argument being the handle to the axis to plot to. There are many solutions online for adding optional arguments to user-defined functions (varargin, inputParser), however they usually…
bhillam
- 193
- 6
8
votes
3 answers
Can I default a function argument to the value of __FILE__ at the caller?
In C++, can I have a defaulted argument to a function which defaults to __PRETTY_FUNCTION___, ___FILE___, and ___LINE__ as defined at the point of the caller and not the point the defaults are supplied in a header file without using macros?
WilliamKF
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7
votes
2 answers
How to retrieve the value(s) of a parameter declared with vararg in an enum in Kotlin
I am new to Kotlin and I have an enum containing many values, those values refer to different states my application has.
Now I need to log something whenever the app enters a state but some state in the enum can log more than one thing (based on…
Cliff Burton
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