Method 'Evaluate' in type 'JSPool.JsEngineWithOwnThread' from assembly 'JSPool, Version=2.0.1.0, Culture=neutral, PublicKeyToken=2fc7775f73072640' does not have an implementation.

[richayrich]

Hi,

I'm trying to get React working, which when installed through NuGet pulled in JSPool automatically.
I'm seeing this exception when loading a .jsx file:

[TypeLoadException: Method 'Evaluate' in type 'JSPool.JsEngineWithOwnThread' from assembly 'JSPool, Version=2.0.1.0, Culture=neutral, PublicKeyToken=2fc7775f73072640' does not have an implementation.]
   JSPool.JsPool.<CreateEngineFactory>b__2_0() +0
   JSPool.JsPool`1.CreateEngine() +19
   JSPool.JsPool`1.PopulateEngines() +18
   JSPool.JsPool`1..ctor(JsPoolConfig`1 config) +191
   React.JavaScriptEngineFactory.CreatePool() +373
   React.JavaScriptEngineFactory..ctor(JsEngineSwitcher jsEngineSwitcher, IReactSiteConfiguration config, IFileSystem fileSystem) +119
   lambda_method(Closure , Object[] ) +128
   React.TinyIoC.TinyIoCContainer.ConstructType(Type requestedType, Type implementationType, ConstructorInfo constructor, NamedParameterOverloads parameters, ResolveOptions options) +682

Any ideas? I've tried downgrading to both 2.0.0 and 0.4.1, which result in slightly different errors.

Thanks,
Rich

[heinzmuller]

@richayrich Have you found any fix/workaround for this error? Got this error today myself

[JoachimL]

We're also struggling with this. Any workarounds?

[richayrich]

@heinzmuller Nope, I haven't progressed past this error.

[Daniel15]

Hmm that's very strange. I'll try to take a look tonight and see what's happening! Are you on ASP.NET Core, or the "classic" ASP.NET? Sent from my phone.

…

On May 11, 2017 8:13 AM, "Rich" ***@***.***> wrote: @heinzmuller <https://github.com/heinzmuller> Nope, I haven't progressed past this error. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#23 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAFnHaRIpNX-CMA6Fc0pJhj47G5ymhxJks5r4yWxgaJpZM4NSOgi> .

[Daniel15]

I'm very confused by this error, because Evaluate does have an implementation:

JSPool/src/JSPool/JsEngineWithOwnThread.cs

Line 236 in 7aea5a2

return RunOnThread(engine => engine.Evaluate(expression));

[heinzmuller]

@Daniel15 Did you manage to replicate it?

[Daniel15]

I haven't been able to replicate this. I tested with .NET Framework 4.5.2:

And with .NET Core 1.1:

Could you please check the file versions of React.Core.dll, JSPool.dll and JavaScriptEngineSwitcher.Core.dll in your site's bin directory? You can view this by right-clicking the assemblies and selecting "Properties"

[Taritsyn]

This error is caused by changes in the JavaScript Engine Switcher version 2.4.0:

In IJsEngine interface was added overloaded versions of the Evaluate, Evaluate<T> and Execute methods, which take the document name as second parameter.

You need to roll back the JavaScript Engine Switcher to version 2.3.X.

[Daniel15]

Thanks for the info @Taritsyn! Ideally backwards-incompatible changes to the public API (like adding new overloads) should be in a new major version (like 3.0.0) as per semver.

I'll bump the JavaScriptEngineSwitcher version in the next JSPool release.

[Taritsyn]

@Daniel15 I recommend you inherit wrappers not from the IJsEngine interface, but from the JsEngineBase base class.

[Taritsyn]

Ideally backwards-incompatible changes to the public API (like adding new overloads) should be in a new major version (like 3.0.0) as per semver.

Next time I will do so. This time I considered that adding new methods is not a serious API change.

[Daniel15]

Should be fixed in JSPool 3.0. I'll publish an updated version of ReactJS.NET that uses JSPool 3.0 shortly.