macros

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . Exactly, macro is not necessary for programming languages. For example, Java works quite fine without macro. Usually macro makes code

问题 How does the PHP Internals TSRMLS_FETCH macro do its job? Per the PHP Manual While developing extensions, build errors that contain "tsrm_ls is undefined" or errors to that effect stem from the fact that TSRMLS is undefined in the current scope, to fix this, declare the function to accept TSRMLS with the appropriate macro, if the prototype of the function in question cannot be changed, you must call TSRMLS_FETCH within the function body. I understand that declaring the function to accept

问题 How does the PHP Internals TSRMLS_FETCH macro do its job? Per the PHP Manual While developing extensions, build errors that contain "tsrm_ls is undefined" or errors to that effect stem from the fact that TSRMLS is undefined in the current scope, to fix this, declare the function to accept TSRMLS with the appropriate macro, if the prototype of the function in question cannot be changed, you must call TSRMLS_FETCH within the function body. I understand that declaring the function to accept

问题 How does the PHP Internals TSRMLS_FETCH macro do its job? Per the PHP Manual While developing extensions, build errors that contain "tsrm_ls is undefined" or errors to that effect stem from the fact that TSRMLS is undefined in the current scope, to fix this, declare the function to accept TSRMLS with the appropriate macro, if the prototype of the function in question cannot be changed, you must call TSRMLS_FETCH within the function body. I understand that declaring the function to accept

问题 I want to match, e.g. an ident 's type to implement a certain trait, how would I do that? Here the basic idea in (incomplete) code: macro_rules! has_trait { ($ ($t : ty), ($x : ident),) => { } } fn trait_test() { let a = vec![1, 2, 3]; let b = 42; let a_iteratable = has_trait!(IntoIterator, a); let b_iteratable = has_trait!(IntoIterator, b); println!("{:?} iterable? {}", a, a_iteratable); println!("{:?} iterable? {}", b, b_iteratable); } I cannot wrap my head around how to say "any type which

问题 I want to match, e.g. an ident 's type to implement a certain trait, how would I do that? Here the basic idea in (incomplete) code: macro_rules! has_trait { ($ ($t : ty), ($x : ident),) => { } } fn trait_test() { let a = vec![1, 2, 3]; let b = 42; let a_iteratable = has_trait!(IntoIterator, a); let b_iteratable = has_trait!(IntoIterator, b); println!("{:?} iterable? {}", a, a_iteratable); println!("{:?} iterable? {}", b, b_iteratable); } I cannot wrap my head around how to say "any type which

问题 I am working on a genetic programming hobby project. I have a function/macro setup that, when evaluated in a setq/setf form, will generate a list that will look something like this. (setq trees (make-trees 2)) ==> (+ x (abs x)) Then it will get bound out to a lambda function #<FUNCTION :LAMBDA (X) ... > via strategic use of functions/macros However, I want to get a bit more effective with this than manually assigning to variables, so I wrote something like this: (setq sample (let* ((trees

问题 I am working on a genetic programming hobby project. I have a function/macro setup that, when evaluated in a setq/setf form, will generate a list that will look something like this. (setq trees (make-trees 2)) ==> (+ x (abs x)) Then it will get bound out to a lambda function #<FUNCTION :LAMBDA (X) ... > via strategic use of functions/macros However, I want to get a bit more effective with this than manually assigning to variables, so I wrote something like this: (setq sample (let* ((trees

问题 I am working on a genetic programming hobby project. I have a function/macro setup that, when evaluated in a setq/setf form, will generate a list that will look something like this. (setq trees (make-trees 2)) ==> (+ x (abs x)) Then it will get bound out to a lambda function #<FUNCTION :LAMBDA (X) ... > via strategic use of functions/macros However, I want to get a bit more effective with this than manually assigning to variables, so I wrote something like this: (setq sample (let* ((trees

问题 I am working on a genetic programming hobby project. I have a function/macro setup that, when evaluated in a setq/setf form, will generate a list that will look something like this. (setq trees (make-trees 2)) ==> (+ x (abs x)) Then it will get bound out to a lambda function #<FUNCTION :LAMBDA (X) ... > via strategic use of functions/macros However, I want to get a bit more effective with this than manually assigning to variables, so I wrote something like this: (setq sample (let* ((trees