问题
The GUI for my company's main product was written in Delphi in the late '90's, and has been updated to Delphi 2007. I'm working with a group to update the Delphi 2007 to XE4.
We still use a number of components from ADL VCL (similar to DevExpress, but now defunct), but have not installed the entire package. Rather, we have the files we need located in a folder seperate from our project folder, and have the path to these files specified in: Tools-Options-Library-browsing path and Project-Options-search path
When I open main, I get the error: "TADLAboutBox not found. Ignore the error and continue?"
The unit "ADLAbout" that defines "ADLAboutBox" is declared in the uses clause in main. Moreover, our project compiles just fine.
How can I get rid of these messages? What might be wrong?
Thanks very much for your advice.
回答1:
ADL VCL is not available for XE4, since it was discontinued some time before XE4 was released. If you have the ADL source code, and have ported it to XE4, then it's plausible that you may have some success.
The error message you describe is symptomatic of not having the design-time packages for the components installed. You'll need to build and install design-time packages for any components that you want to interact with at design-time.
回答2:
The component is not installed in the IDE, so when you open a form that uses that component you get an error.
But the source to the component can be found so when you compile it will do that without problems.
To get rid of the error you must install the component in the IDE.
来源：https://stackoverflow.com/questions/17927402/delphi-xe4-class-not-found-but-compiles-fine