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I can't understand such syntax in https://github.com/hmenke/boost_matheval/blob/master/src/qi/parser.hpp#L43
struct bar {
bar() {}
};
template<typename _T>
class foo {
public:
foo() {}
};
...
foo<bar()> fb;
...
What is the type of _T in the specialization of the templates foo? How to use _T in foo?
731
Classes have parenthesis because when initially called you're most likely looking to execute the creation of a new object of that class. Methods will have parenthesis because once created they're meant to be called. I hope this helps.
{} are used to define a dictionary in a "list" called a literal parentheses in java: Parentheses are used for two purposes: (1) to control the order of operations in an expression, and (2) to supply parameters to a constructor or method. ................. and many more in simple: A parenthesis is a punctuation mark ...
class C: Function/method definitions always take parentheses, even if you don't define parameters. If you don't use them, you'll get a SyntaxError. Later, after the definition of a class/function/method in the code, just writing the name will point you to the class/function/method.
Parameters and Arguments Parameters are specified after the method name, inside the parentheses.
It's the type of a function. When you declare
bar function();
I.e., a function taking no arguments and returning a bar, then function has a type, and it's bar(). _T stands for it. As though you have an alias
using _T = bar();
or
typedef bar _T();
It's not an uncommon type to see. For instance, function types are what std::function accepts. How to use it depends on the purpose of the class template, and how it's potentially specialized.
98
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