c# - NET4 features: should casting generic IEnumerable to IEnumerable be possible? -



c# - NET4 features: should casting generic IEnumerable<T> to IEnumerable<MoreSpecificT> be possible? -

if have internal method in .net 4 library (running on mono here):

protected internal ienumerable<kscomponent> getcomponentsbytype(type componenttype) { homecoming this.componentsdic [componenttype]; }

and expose generic parameter simple usage. have done far , working:

public ienumerable<tcomponenttype> getcomponentsbytype<tcomponenttype>() tcomponenttype : kscomponent { homecoming this.getcomponentsbytype (typeof(tcomponenttype)).cast<tcomponenttype>(); }

however, shouldn't .net 4.0 work:

public ienumerable<tcomponenttype> getcomponentsbytype<tcomponenttype>() tcomponenttype : kscomponent { homecoming (ienumerable<tcomponenttype>)this.getcomponentsbytype (typeof(tcomponenttype)); }

edit:

kscomponent base of operations class, tcomponenttype can (e.g.) ksmovecomponent, subclasses kscomponent. situation have class code above holds list of kscomponent specific type, instance:

typeof(ksmovecomponent) maps list<kscomponent>(). elements of list of type ksmovecomponent. i'd have list<kscomponent> beingness cast list<ksmovecomponent> straight instead of using linq.cast() extension.

it's coming downwards question: have list of cars , can 100% sure mercedes - why can't list of mercedes then? :-)

covariance allows cast enumerable more generic version.

the generic status on other hand allows replace generic type more restrictive.

so why work? seems 2 of them going in 2 different directions - no?

c# .net .net-4.0 mono covariance

Comments

Post a Comment

Popular posts from this blog

web services - java.lang.NoClassDefFoundError: Could not initialize class net.sf.cglib.proxy.Enhancer -

web services - java.lang.NoClassDefFoundError: Could not initialize class net.sf.cglib.proxy.Enhancer - when trying request rest service @ time of response getting exception.. feb 21, 2013 2:34:49 pm com.sun.jersey.spi.container.containerresponse mapmappablecontainerexception severe: exception contained within mappablecontainerexception not mapped response, re-throwing http container java.lang.noclassdeffounderror: not initialize class net.sf.cglib.proxy.enhancer @ org.hibernate.proxy.pojo.cglib.cgliblazyinitializer.getproxyfactory(cgliblazyinitializer.java:117) @ org.hibernate.proxy.pojo.cglib.cglibproxyfactory.postinstantiate(cglibproxyfactory.java:43) @ org.hibernate.tuple.entity.pojoentitytuplizer.buildproxyfactory(pojoentitytuplizer.java:162) @ org.hibernate.tuple.entity.abstractentitytuplizer.<init>(abstractentitytuplizer.java:135) @ org.hibernate.tuple.entity.pojoentitytuplizer.<init>(pojoentitytuplizer.java:55) @ org.hibernate.tuple.e...
Read more

Accessing MATLAB's unicode strings from C -

Accessing MATLAB's unicode strings from C - how can access underlying unicode info of matlab strings through matlab engine or mex c interfaces? here's example. let's set unicode characters in utf-8 encoded file test.txt, read as fid=fopen('test.txt','r','l','utf-8'); s=fscanf(fid, '%s') in matlab. now if first feature('defaultcharacterset', 'utf-8') , c engevalstring(ep, "s") , output text file utf-8. proves matlab stores unicode internally. if mxarraytostring(enggetvariable(ep, "s")) , unicode2native(s, 'latin-1') give me in matlab: non-latin-1 characters replaced character code 26. need getting access underlying unicode info c string in unicode format (utf-8, utf-16, etc.), , preserving non-latin-1 characters. is possible? my platform os x, matlab r2012b. addendum: documentation explicitly states "[mxarraytostring()] supports multibyte encoded characters...
Read more

javascript - mongodb won't find my schema method in nested container -

javascript - mongodb won't find my schema method in nested container - i trying access method of schema stored within mixed container. here situation : have cases model can many different things, have schema each of these things stored in "casecontent" mixed property. var caseschema = mongoose.schema({ casecontent : {}, object : {type:string, default : "null"}, collision : {type : boolean, default : false} }); the casecontent property filled model of 1 of schemas, 1 exemple : var treeschema = new mongoose.schema({ applecount : {type : number, default : 3} }); treeschema.methods.dostuff = function (data) { console.log('hey, listen'); homecoming true; }; then, want utilize method of schema original container : caseschema.methods.dostuff = function (data) { if (this.casecontent.dostuff !== undefined) { this.casecontent.dostuff(); console.log('it worked'); } else { ...
Read more