Method Interception using Reflection in C# -


i wrote abstract class uses reflection find fields marked attribute in constructor, this:

[attributeusage(attributetargets.field)] public class trackedfield : attribute {}  public class atrackedobject {     public atrackedobject() {         type objtype = this.gettype();         foreach(fieldinfo f in objtype.getfields()) {             if(f.isdefined(typeof(trackedfield)), false)) {                 //add field list keep tabs on periodically             }         }     } }

what do, is:

  1. create attribute, trackedmethod
  2. in constructor, in same fashion trackedfields, find methods tagged trackedmethod
  3. change method when gets called, method inside atrackedobject gets called first or instead, either replacing method entirely or injecting code it, without breaking ability @ least see original method call was, including parameters
  4. no third-party libaries, , should .net 3.5 compatible

i have seen number of se threads discussing how this, , of answers relied on being able use third party library - however, none of questions seemed match use case - can ensure 100% every object needs have methods tracked inherit class tracking.

i don't know sure possible, wondering since ioc/aop libraries postsharp , others exist, surely must operate kind of mechanism - assume reflection.emit plays part - what, , how?

here similar questions, did not have seemed me answers specific scenario, or relied on third party libraries:

custom-attribute-to-process-info-before-a-method-is-called

how-do-i-intercept-a-method-call-in-c (this helpful, missing crucial component of how inject code

intercept-method-calls

is there way make technique (attribute -> base class constructor -> reflection -> method interception) viable?

could work need?

[attributeusage(attributetargets.field)] public class trackedfield : attribute { }  public class atrackedobject {     public atrackedobject()     {         type objtype = this.gettype();         foreach (fieldinfo f in objtype.getfields())         {             if (f.isdefined(typeof(trackedfield), false)) {                 if (f.fieldtype == typeof(action))                 {                     var currentvalue = f.getvalue(this) action;                     action newvalue = () =>                     {                         console.writeline($"tracking {f.name}");                         currentvalue.invoke();                     };                      f.setvalue(this, newvalue);                 }             }         }     }      [trackedfield]     public action somemethod = () => console.writeline("some method called"); }

this done simple action property extended use func<>

edit: forgot include usage , output.

usage:

static void main(string[] args) {     var obj = new atrackedobject();     obj.somemethod();      console.read(); }

output:

tracking somemethod method called

Comments

Post a Comment

Popular posts from this blog

angular - Ionic slides - dynamically add slides before and after -

hi i'm using ngfor create set of 3 slides while starting in middle i'm guaranteed able slide left or right on start. when slide right can simple listen reachedend , push slide array i'm looping. but have problem adding slide beginning. if same above , use e.g. array.unshift() or spread add item beginning, view think it's on position 0 , snaps view new slide. the code below work animates slide change index 1. slide = [0,1,2] //example loop slidechanged(event) { if(this.slides.isbeginning()){ this.slide = [this.slide[0]-1, ...this.slide]; this.slides.update(); this.slides.slideto(1) } } <ion-slides [initialslide]="1" (ionslidedidchange)="slidechanged($event)"> <ion-slide *ngfor="let item of slide"> <h1>slide {{item}}</h1> </ion-slide> </ion-slides> any appreciated! you can using ionslidenextend , ionslideprevend events slides . please...
Read more

Add a dynamic header in angular 2 http provider -

i have http interceptor built via tutorial https://scotch.io/@kashyapmukkamala/using-http-interceptor-with-angular2 the problem need have dynamic header changes automatically once changes 'mode' in app. service able tell interceptor change header, or have interceptor pull header (which string)from service each request. able throwing away patch method, call http.patch('new header string') set header string. call in service controls 'mode' setting. wondering if there way interceptor pull recent value service each request or if can add method http provider via interceptor? i've tried call service in interceptor each request returns undefined. because creating new instance of service or copying value before service fired , loaded/changed data. i don't want pass header string every http provider call because defeats purpose of having interceptor, id able set once changes or have provider fetch service before makes request. tl;dr : need add autom...
Read more

minify - Minimizing css files -

i want know how css files can minimized. currently, using external sites css minifier compress css files. however, after removing whitespaces, comments, etc, file sizes reduced 10-15%. how frameworks bootstrap manage make minimized versions kilobytes. as example, css is: body { background-color: #ff0; } the reduction goes 28 bytes 22 bytes other css files have lot more characters still smaller this. actually minifying code means it's remove thing code white space characters new line characters comments block delimiters it reduces amount of code has transferred on web , speed site load fastly.but unreadable format.
Read more