Boost-pp: how to determine if a macro parameter is a tuple -


a tuple comma-separated list enclosed parens, e.g.

() (,) (thing,) (2,3)

if have 

#define istuple(x) \\...

i'd istuple(nope) resolve 0 , istuple((yep)) resolve 1.

[fwiw, have _rtfm_'d plenty.]

it done in preprocessing library little work, variadic macro data library (added boost since question posted) has ready-made solution. boost_vmd_is_tuple, defined in boost/vmd/is_tuple.hpp, should you're looking for:

#include <iostream>  #include <boost/vmd/is_tuple.hpp>  #if boost_vmd_is_tuple() != 0   #error boost_vmd_is_tuple() != 0 #endif  #if boost_vmd_is_tuple(nope) != 0   #error boost_vmd_is_tuple(nope) != 0 #endif  #if boost_vmd_is_tuple((yep)) != 1   #error boost_vmd_is_tuple((yep)) != 1 #endif  #if boost_vmd_is_tuple(()) != 1   #error boost_vmd_is_tuple(()) != 1 #endif  #if boost_vmd_is_tuple((,)) != 1   #error boost_vmd_is_tuple((,)) != 1 #endif  #if boost_vmd_is_tuple((thing,)) != 1   #error boost_vmd_is_tuple((thing,)) != 1 #endif  #if boost_vmd_is_tuple((2,3)) != 1   #error boost_vmd_is_tuple((2,3)) != 1 #endif  static_assert(boost_vmd_is_tuple() == 0,"boost_vmd_is_tuple() != 0"); static_assert(boost_vmd_is_tuple(nope) == 0,"boost_vmd_is_tuple(nope) != 0"); static_assert(boost_vmd_is_tuple((yep)) == 1,"boost_vmd_is_tuple((yep)) != 1"); static_assert(boost_vmd_is_tuple(()) == 1,"boost_vmd_is_tuple(()) != 1"); static_assert(boost_vmd_is_tuple((,)) == 1,"boost_vmd_is_tuple((,)) != 1"); static_assert(boost_vmd_is_tuple((thing,)) == 1,"boost_vmd_is_tuple((thing,)) != 1"); static_assert(boost_vmd_is_tuple((2,3)) == 1,"boost_vmd_is_tuple((2,3)) != 1");  int main(void) {     using std::cout;     using std::endl;     cout << "boost_vmd_is_tuple() == " << boost_vmd_is_tuple() << endl;     cout << "boost_vmd_is_tuple(nope) == " << boost_vmd_is_tuple(nope) << endl;     cout << "boost_vmd_is_tuple((yep)) == " << boost_vmd_is_tuple((yep)) << endl;     cout << "boost_vmd_is_tuple(()) == " << boost_vmd_is_tuple(()) << endl;     cout << "boost_vmd_is_tuple((,)) == " << boost_vmd_is_tuple((,)) << endl;     cout << "boost_vmd_is_tuple((thing,)) == " << boost_vmd_is_tuple((thing,)) << endl;     cout << "boost_vmd_is_tuple((2,3)) == " << boost_vmd_is_tuple((2,3)) << endl;      return 0; }

output:

boost_vmd_is_tuple() == 0 boost_vmd_is_tuple(nope) == 0 boost_vmd_is_tuple((yep)) == 1 boost_vmd_is_tuple(()) == 1 boost_vmd_is_tuple((,)) == 1 boost_vmd_is_tuple((thing,)) == 1 boost_vmd_is_tuple((2,3)) == 1

(http://coliru.stacked-crooked.com/a/6e41eaf17437c5d5)


Comments

Post a Comment

Popular posts from this blog

commonjs - How to write a typescript definition file for a node module that exports a function? -

consider, toml node module can use: // toml.d.ts declare module toml { export function parse(value:string):any; } declare module "toml" { export = toml; } then: /// <reference path="../../../../../defs/toml/toml.d.ts"/> import toml = require('toml'); toml.parse(...); however, node module export single function, such 'glob' ( https://github.com/isaacs/node-glob ). the node usage of module be: var glob = require("glob") glob("*.js", {}, callback(err, files) { ... }); you'd naively expect this: // glob.d.ts declare function globs(paths:string, options:any, callback:{(err:any, files:string[]):void; ...but because typescripts 'import' semantics bit strange, seems can use 'import .. = require()' statement alias modules . trying call: /// <reference path="../../../../../defs/glob/glob.d.ts"/> import blog = require('glob'); results in: error ts2072: mod...
Read more

openid - Okta: Failed to get authorization code through API call -

i'm integrating okta own idp server using okta's api. i'm implementing authorization code flow following steps below: in own server, use /api/v1/authn endpoint sessiontoken. use sessiontoken obtain authorization calling endpoint: /oauth2/v1/authorize?client_id=" + clientid + "&sessiontoken=" + sessiontoken + "&response_type=code&response_mode=query&scope=openid&redirect_uri=" + redirecturl + "&state=evanyang&nonce=" it's supposed return response status code 302 , location header containing redirect url code value. however, keep getting response status code 200 , without location header, html body saying "you using unsupported browser." , "javascript disabled on browser." according api documentation: http://developer.okta.com/docs/api/resources/oidc.html#authentication-request , sessiontoken parameter sufficient this: an okta one-time sessiontoken. allows api-based ...
Read more

ios - Change Storyboard View using Seague -

i have following code checks connection server, , depending on want change views if no connection found. nsstring *connect = [nsstring stringwithcontentsofurl:[nsurl urlwithstring:@"http://myserver.com"] encoding:nsutf8stringencoding error:nil]; if (connect == null) { [self performseguewithidentifier:@"network_failure" sender:self]; } else { // other code here } my problem not change views. have added storyboard segue between 2 views identifier of network_failure . not have navigation controller or that, problem? thanks help! no not problem. first of all, in objectivec exists nil object oriented null . must use that. so: if(connect == nil) or better: if(!connect) so due fact nil not same of null , probably code does't enter in if scope . you have been able discover breakpoint. anyway: be sure set trigger segue (line) 2 view controller , , name network_failure (that not best name. should instead view1toview2 ) as, m...
Read more