我试图理解#If ... #Then [英] Am trying to understand #If ... #Then

问题描述

我想在调试窗口中测试一些代码...


选项比较数据库

Option Explicit


Private Sub Command0_Click（）

#If Win32然后

MsgBox"嘿！它是WIN32。"

#End如果

结束子


私有子Command1_Click（）

#If Win16然后

MsgBox"嘿！它是WIN16。"

#End如果

结束子


我没有走得太远。 A97帮助没有打破它，简化了指令让我掌握它。确切地说，＃If指令

呢？而且，Win32和Win16的值来自何处？

它们是内在常量吗？

I would like to test some of this code in the debug window...

Option Compare Database
Option Explicit

Private Sub Command0_Click()
#If Win32 Then
MsgBox "Hey! It''s WIN32."
#End If
End Sub

Private Sub Command1_Click()
#If Win16 Then
MsgBox "Hey! It''s WIN16."
#End If
End Sub

I''m not getting very far. A97 Help doesn''t break it down, simplifying
the directive for me to grasp it. What, exactly, does #If directive
do? And, where do the values for Win32 and Win16 come from?
Are they intrinsic constants?

推荐答案

>我走得不远。 A97帮助没有分解，简化了

> I''m not getting very far. A97 Help doesn''t break it down, simplifying

指令让我掌握它。究竟#If指令究竟是什么呢？而且，Win32和Win16的值来自哪里？
它们是内在常量吗？

the directive for me to grasp it. What, exactly, does #If directive
do? And, where do the values for Win32 and Win16 come from?
Are they intrinsic constants?

看看这段代码：


================================

选项比较数据库

选项明确


#Const IWantLateBinding = True


#IfantLateBinding然后

将myWord称为对象

#Else

将myWord调暗为Access.Application

#End如果


Private Sub Form_Load（）

#IfantLateBinding然后

设置myWord = CreateObject（" Access.Application"）

#Else

设置myWord =新的Access.Application

#End如果

End Sub

======= =========================


#If ....＃Then .. ..＃Else ....＃End If"构造是条件

编译的一部分。

#Const ....声明是另一部分。


-

PBsoft di Gabriele Bertolucci
www.pbsoft.it

skype：pbsoftsolution

Look at this piece of code:

================================
Option Compare Database
Option Explicit

#Const IWantLateBinding = True

#If IWantLateBinding Then
Dim myWord as Object
#Else
Dim myWord as Access.Application
#End If

Private Sub Form_Load()
#If IWantLateBinding Then
Set myWord = CreateObject("Access.Application")
#Else
Set myWord = New Access.Application
#End If
End Sub
================================

The "#If....#Then....#Else....#End If" construct is part of "conditional
compilation".
The "#Const...." declaration is the other part.

--
PBsoft di Gabriele Bertolucci
www.pbsoft.it
skype: pbsoftsolution

#If ... #End如果construct是一个条件编译测试。


看到它效果的最简单方法是创建自己的条件

编译常数。


例如

''这是条件编译常量。

#Const InDebug = False


函数TestInDebug（）

#If InDebug然后

MsgBox"我们正在调试"

#Else

MsgBox我们没有调试

#End如果

结束功能


现在，你可能已经意识到你可以用正常的方式获得相同的效果

如果...结束如果构造但是考虑以下作为常见问题的解决方案
问题。
/>
创建对Microsoft Word的引用，然后使用以下代码： -


#Const InDebug = True


函数TestInDebug（）

#If InDebug然后

Dim oWord As Word.Application


设置oWord =新Word.Application

#Else

将对象视为对象


设置oWord = CreateObject（" Word.Application"）

#End如果


''这个位不需要有条件地编译

用oWord

.Visible =真的

。错误确认

结束


设置oWord = Nothing

结束功能


首先要注意的是

#Const InDebug = True


....然后当行

oWord.Quit False


....输入我们得到上下文敏感的下拉菜单，如果另一方面

＃ Const InDebug = False


....然后我们不会


第二次要注意的是，虽然我们有对Word的引用，但

代码运行得非常愉快，条件编译常量设置为

True或False。如果我们删除对toWord的引用并且条件

编译常量设置为False则代码将运行，如果在另一个

手上我们将条件编译常量设置为True然后我们得到一个

错误用户定义的类型未定义和oWord As Word.Application。

突出显示


在模块中定义条件编译常量使其保持不变

仅在定义的模块中具有范围然而，如果您转到

工具菜单并选择<您的应用程序名称>属性"从菜单中你可以定义条件编译常量（作为分号分隔

列表），它们具有应用程序级别范围。

-


Terry Kreft

" MLH" < CR ** @ NorthState.net>在留言中写道

news：5t ******************************** @ 4ax.com ...

The #If... #End If construct is a conditional compilation test.

The easiest way to see it''s effect is to create your own conditional
compilation constant.

e.g.
'' This is the conditional compilation constant.
#Const InDebug = False

Function TestInDebug()
#If InDebug Then
MsgBox "We''re debugging"
#Else
MsgBox "We''re not debugging"
#End If
End Function

Now, you probably realise that you can get the same effect with a normal
If... End If construct but consider the following as a solution to a common
problem.

Create a reference to Microsoft Word and then use the following code:-

#Const InDebug = True

Function TestInDebug()
#If InDebug Then
Dim oWord As Word.Application

Set oWord = New Word.Application
#Else
Dim oWord As Object

Set oWord = CreateObject("Word.Application")
#End If

'' This bit doesn''t need to conditionally compile
With oWord
.Visible = True
.Quit False
End With

Set oWord = Nothing
End Function

The first thing to notice is if
#Const InDebug = True

.... then when the line
oWord.Quit False

.... is typed we get context sensitive dropdowns, if on the other hand
#Const InDebug = False

.... then we don''t

The second thing to notice is that while we have the reference to Word the
code runs quite happily with the conditional compilation constant set to
True or False. If we remove the reference toWord and the conditional
compilation constant is set to False then the code will run, if on the other
hand we set the conditional compilation constant to True then we get an
error "User-defined type not defined" and "oWord As Word.Application" is
highlighted

Defining a conditional compilation constant in a module makes that constant
have scope only in the module it is defined in, if however you go to the
Tools menu and choose "<Your Application name> Properties" from the menu you
can define conditional compilation constants (as a semi-colon delimited
list) which have application level scope.
--

Terry Kreft
"MLH" <CR**@NorthState.net> wrote in message
news:5t********************************@4ax.com...

我想在调试窗口中测试一些代码...

选项比较数据库
选项明确
#If Win32然后
MsgBox嘿！它是WIN32。
#End如果
结束Sub

私人Sub Command1_Click（）
#If Win16那么
MsgBox"嘿！这是WIN16。
#End如果
结束Sub

我没有走得太远。 A97帮助并没有打破它，简化了我掌握它的指令。究竟#If指令究竟是什么呢？而且，Win32和Win16的值来自哪里？
它们是内在常量吗？

I would like to test some of this code in the debug window...

Option Compare Database
Option Explicit

Private Sub Command0_Click()
#If Win32 Then
MsgBox "Hey! It''s WIN32."
#End If
End Sub

Private Sub Command1_Click()
#If Win16 Then
MsgBox "Hey! It''s WIN16."
#End If
End Sub

I''m not getting very far. A97 Help doesn''t break it down, simplifying
the directive for me to grasp it. What, exactly, does #If directive
do? And, where do the values for Win32 and Win16 come from?
Are they intrinsic constants?

谢谢Gabriele的解释和

例子。我有一个带有自己的类模块的表单。

表单只有2个按钮，每个按钮的代码运行

如下所示。我没有理解的是，
理解的是，WIN16和WIN32''编译器常量''/ b $ b的值只能在#If的范围内读取 - #Then < br $>
构建 - 以及其他任何地方。


Terry Kreft也提供了一个很好的例子。你知道

特里在帖子的评论中提到了什么特定的常见问题

？

Thanks, Gabriele, for the explanation and the
example. I have a form with its own class module.
The form has only 2 buttons and the code running
for each button is shown below. What I didn not
understand was that the values of WIN16 and WIN32 ''compiler constants''
can be read ONLY within the confines of an #If - #Then
construct - and nowhere else.

Terry Kreft also provided a fine example. Do you know
what specific common problem Terry was referring to
early in his comments on the post?

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