Object Oriented Programming - Leaving properties from objects empty.
4 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Hi everybody! I am writing the following code:
classdef Value0_1
properties
Price
Earnings
ddd
BookValue
P_E_Calc
P_B_Calc
end
methods
function PE=Value0_1(price,earnings,Ddd)
if nargin <2
PE.Price=price;
PE.Earnings=earnings;
PE.ddd=Ddd;
end
end
end
end
Now, I would like to create an object by typing in the command Window PriceEarnings=Value0.1(555,555,~). the following error comes: Error: Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.
--> How can I leave the argument Ddd empty?
0 Commenti
Risposta accettata
Matt J
il 28 Ago 2018
Modificato: Matt J
il 28 Ago 2018
The call should look like PriceEarnings=Value0_1(555,555) and the code for the constructor should look like,
function PE=Value0_1(price,earnings,Ddd)
if nargin >=1
PE.Price=price;
end
if nargin>=2
PE.Earnings=earnings;
end
if nargin>=3
PE.ddd=Ddd;
end
end
4 Commenti
Adam
il 28 Ago 2018
I tend to use
if exist( 'earnings', 'var' ) && ~isempty( earnings )
validateattributeS( earnings,... )
else
earnings = someDefaultValue;
end
nowadays rather than using nargin, for this purpose. Then I pass in empty, like Matt J has done which causes it to use the default value I supply. I occasionally use the inputParser, but I've generally only done it when I allow 'name', 'value' pairs of any of my properties to be set like in many Matlab functions.
Più risposte (1)
BdS
il 29 Ago 2018
1 Commento
Adam
il 29 Ago 2018
It's hard to know without more specific examples, but you can create class hierarchies where a derived class will extend the base class, which sounds like what you may want, for the extra properties that may be empty in some objects otherwise. Obviously if every property is different then you would just want two independent classes, but I am assuming there is commonality too.
Vedere anche
Categorie
Scopri di più su Argument Definitions in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!