Delphi2005学习笔记4——再谈NameSpace和Dll以及Package

Executive Summary

•          Namespaces do not affect Delphi for Win32.

•          Namespaces are produced based on the unit name as follows:

•          If a unit name is dotted then the unit name up to the last dot is used.

•          If it is not dotted then the default namespace is used.

•          If there is no default namespace then the unit name is used.

•          Code converted from Delphi 8 may require some modifications.

•          Always use Packages not Libraries to create shareable assemblies.

•          Delphi will always refer to types by their full unit name.

•          Other languages will need to refer to types using their namespace.

•          ASP.NET declarations, configuration files and .NET reflection always refer to types by their namespace.

•          If multiple units emit a public type with the same name into the same namespace, the assembly may be unusable
　　
　　

Borland has always recommended not using library projects to create assemblies. In Delphi 2005, the compiler is stricter and will no longer allow you to compile an application referencing a Delphi ‘library’.
　　Always use a package project to create .NET assemblies.
　　
　　

However, as with anything, there are exceptions to the rule and there are several situations where you need to use the namespace even though you are coding in Delphi.

One example is when you are using tags in ASPX, ASCX or ASMX files. If you create a web page called TWebForm in the file Application.­Pages.­WebForm1.­­pas then the page tag would be:

%@Page Language="c#" Codebehind="WebForm1.pas" Inherits="Application.Pages.TWebForm1"%

Another is when passing type information to .NET in the form of strings, especially when using reflection based APIs and configuration files:

var c:TypeConverter;

c:=Assembly.CreateInstance('Sample.Controls.TConverter');

This slight difference commonly trips people up and is something you need to be careful of, especially when porting code from Delphi 8 or converting code from other languages.
　　
　　这就解释了我原来的疑问，在D2005中，新建一个.Net Dll，编译，在别的编译器中(C#)，可以使用，但是在Delphi中自己却不能用，虽然用薄可以解决问题，但是包中添加资源很不方便，真是不知道Borland是怎么想的。