Delphi Unicode移植（从Delphi2007及一下版本移植到Delph2009以上）

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Delphi Unicode Migration for

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customers. While this important development is opening new markets for your software, in

some cases it presents a challenge for existing applications and development techniques,

especially where code has included assumptions about the size of strings.

insights of numerous Delphi developers who have already made the journey. It begins with

a general introduction of the issues, followed by a brief overview of Unicode basics. This is

followed by a systematic look at the various aspects of your applications that may require

attention, with examples and suggestions based on real world experience. A list of

inlining and nested classes (Delphi 2005) and generics (Delphi 2009), enabling Unicode

nearly every Delphi application. Specifically, the definitions for the String, Char, and PChar

types changed.

extensive consideration for the impact that these changes would have for existing

simply as Steve, noted, "I think PChars and Strings should never have changed meaning.

It was a bit of a no-win situation."

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In the end, changing the meaning of String, Char, and PChar was determined to be the

least disruptive path, though not without consequences. On the plus side, Embarcadero

instantly enabled RAD Studio developers to build world class applications that treat both

the graphical interfaces and the data they help manipulate in a globally-conscious manner,

removing substantial barriers to building and deploying applications in an increasingly

encounter migration issues that require changes to the existing code or require upgrades

to newer versions of third-party component sets or libraries. The same is true when

upgrading to Delphi 2009 or later. Some upgrades will be easier, and some will be more

PChar) or Delphi 2 (String), it is fair to say that migrating an existing application to Delphi

2009 or later requires more effort than any previous migration.

to share their insights, advice, and stories of Unicode migration. What I received in

response was fascinating.

some publish highly popular third-party component sets and tools used by application

developers. Yet others are highly respected authorities on Delphi, developers who speak

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Regardless of whether a particular migration was smooth or challenging, a set of common

sharing those with you.

But the story does not end with the publication of this white paper. I hope to continue to

descriptions. If you are already familiar with Unicode, have a basic understanding of UTF-8

and UTF-16, and know the difference between code pages and code points, you should

either skip this section, or quickly skim if for terms you are unfamiliar with.

for Unicode has two complementary, though distinct, implications for those applications

you build. The first is related to how strings are treated differently in code written in Delphi

2009 and later versus how they are treated in earlier versions of Delphi. The second relates

Implementing support for multiple languages and character sets is beyond the scope of

this paper, and will not be discussed further.

Unicode is a standard specification for encoding all of the characters and symbols of all of

Similar to the ANSI (American National Standards Institute) code standard character set,

which represents both control characters (such as tab, line feed, and form feed) and

printable characters of the 26 character Latin alphabet, Unicode assigns at least one

unique number to every character.

Each control character, character, or symbol in Unicode is assigned a numeric value, called

its code point. The code point for a given character, once assigned by the Unicode

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unique, immutable name, which in this case is ‘LATIN CAPITAL LETTER A.’ Both of these

can never be changed, ensuring that today’s encoding can be relied upon indefinitely.

Each code point can be represented in either one, two, or four bytes, with the bulk of

BMP (you'll want to remember these initials, as they will come up a lot in this paper).

To make things somewhat more complicated, the Unicode standard allows some

For example, the character ö can be represented as $00F6. This character is referred to as