possible to execute code contained in a string ?

Re: possible to execute code contained in a string ?

Do you mean that you want a C# method that would take a string
containing some C# code and then execute it? Or do you mean you want a
C# method that would take an SQL command as a string and execute
against a database?

Re: possible to execute code contained in a string ?

The former.


"Mohammad" <m@abdulfatah.n et> wrote in message
news:1112057880 .276639.5950@o1 3g2000cwo.googl egroups.com...[color=blue]
> Do you mean that you want a C# method that would take a string
> containing some C# code and then execute it? Or do you mean you want a
> C# method that would take an SQL command as a string and execute
> against a database?
>[/color]

Re: possible to execute code contained in a string ?

Short answer is no, there's isn't a built in function in C# that would
evaluate a C# expression stored in a string.

Long answer is still no, but it can be done. You basically have two
choices: use classes in the System.Reflecti on.Emit namespace to
implement this functionality yourself, or write your own mini
interpreter to parse and execute the subset of the C# expression
languange that you are interested in. You might want to use the ANTLR
parser generator(http://www,antlr.org/). I have used it once before,
and I found it to be quite impressive.

Be forewarned though, both options would constitute an act of
self-flagellation and loathing unlike any other. So, unless you
absolutely must have this functionality, or if you have some very
sinister sins that you want to repent, then don't do it!

Re: possible to execute code contained in a string ?

There's plenty of scripting languages out there that you could
integrate into your C# application to do this - such as Perl (and
probably VBA?).

That might suit your goals?

Re: possible to execute code contained in a string ?

That's possible : have a look to System.CodeDom and System.CodeDom. Compiler.

I have found an example I wrote few months ago :
assume 'usingList' is an arraylist with all using statement (without using
keyword, "System.Xml " for example)
assume 'importList' is an arraylist with all dll name that are necessary for
compilation ("system.dll " for example)
assume 'source' is the source code you want to compile
assume 'classname' is the name of the class you want to compile
assume 'methodname' is the name of the method

Have a look to the following code :
---------------------------------------
//Create method
CodeMemberMetho d pMethod = new CodeMemberMetho d();
pMethod.Name = methodname;
pMethod.Attribu tes = MemberAttribute s.Public;
pMethod.Paramet ers.Add(new
CodeParameterDe clarationExpres sion(typeof(str ing[]),"boxes"));
pMethod.ReturnT ype=new CodeTypeReferen ce(typeof(bool) );
pMethod.Stateme nts.Add(new CodeSnippetExpr ession(@"
bool result=true;
try {
"+source+@"
} catch {
result=false;
}
return result;
"));

//Crée la classe
CodeTypeDeclara tion pClass = new
System.CodeDom. CodeTypeDeclara tion(classname) ;
pClass.Attribut es = MemberAttribute s.Public;
pClass.Members. Add(pMethod);

//Crée le namespace
CodeNamespace pNamespace = new CodeNamespace(" myNameSpace");
pNamespace.Type s.Add(pClass);
foreach(string sUsing in usingList) pNamespace.Impo rts.Add(new
CodeNamespaceIm port(sUsing));

//Create compile unit
CodeCompileUnit pUnit = new CodeCompileUnit ();
pUnit.Namespace s.Add(pNamespac e);

//Make compilation parameters
CompilerParamet ers pParams = new
CompilerParamet ers((string[])importList.ToA rray(typeof(str ing)));
pParams.Generat eInMemory = true;

//Compile
CompilerResults pResults=(new
CSharpCodeProvi der()).CreateCo mpiler().Compil eAssemblyFromDo m(pParams,pUnit )
;
if (pResults.Error s != null && pResults.Errors .Count>0) {
foreach(Compile rError pError in pResults.Errors )
MessageBox.Show (pError.ToStrin g());
result =
pResults.Compil edAssembly.Crea teInstance("myN ameSpace."+clas sname);
}
---------------------------------------

for an example,
if 'usingList' equals {"System.Text.R egularExpressio ns"}
if 'importList' equals {"System.dll "}
if 'classname' equals "myClass"
if 'methodName' equals "myMethod"
if 'source' equals "
string pays=@"ES
FR
EN
"
Regex regex=new Regex(@"^[A-Za-z]{2}$");
result=regex.Is Match(boxes[0]);
if (result) {
regex=new Regex(@"^"+boxe s[0]+@".$",RegexOpt ions.Multiline) ;
result=regex.Ma tches(pays).Cou nt!=0;
}

then, the code that will be compiled will be the following :

using System.Text.Reg ularExpressions ;
namespace myNameSpace {
public class myClass {
public bool myMethod(string[] boxes) {
bool result=true;
try {
string pays=@"ES
FR
EN
"
Regex regex=new Regex(@"^[A-Za-z]{2}$");
result=regex.Is Match(boxes[0]);
if (result) {
regex=new Regex(@"^"+boxe s[0]+@".$",RegexOpt ions.Multiline) ;
result=regex.Ma tches(pays).Cou nt!=0;
}
} catch {
result=false;
}
return result;
}
}
}

---------------------------------------------------

Hope it helps,

Ludovic Soeur.




"John Grandy" <johnagrandy-at-yahoo-dot-com> a écrit dans le message de
news:O1xRF6$MFH A.2136@TK2MSFTN GP14.phx.gbl...[color=blue]
> The former.
>
>
> "Mohammad" <m@abdulfatah.n et> wrote in message
> news:1112057880 .276639.5950@o1 3g2000cwo.googl egroups.com...[color=green]
> > Do you mean that you want a C# method that would take a string
> > containing some C# code and then execute it? Or do you mean you want a
> > C# method that would take an SQL command as a string and execute
> > against a database?
> >[/color]
>
>[/color]