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>Pgtcl Reference Manual: The PostgreSQL Tcl Interface</TH
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><A
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></A
>Chapter 3. Loading <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> into an Application</H1
><BLOCKQUOTE
CLASS="ABSTRACT"
><DIV
CLASS="ABSTRACT"
><P
></P
><A
NAME="AEN480"
></A
><P
>This chapter describes how to use <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> with
your Tcl application. Before using <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> commands,
you must load the <TT
CLASS="FILENAME"
>libpgtcl</TT
> library into your Tcl
application. There are three approaches to doing this, but care must be
taken because of the dependency on the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
client library <TT
CLASS="FILENAME"
>libpq</TT
>.
</P
><P
>This chapter also describes <SPAN
CLASS="APPLICATION"
>pgtclsh</SPAN
> and
<SPAN
CLASS="APPLICATION"
>pgwish</SPAN
>, which are Tcl and Tcl/Tk shells
built with <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
>.
</P
><P
>This chapter only applies to the <SPAN
CLASS="APPLICATION"
>pgtcl-ng</SPAN
>
implementation of <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
>. For other
implementations, check the included documentation.
</P
><P
></P
></DIV
></BLOCKQUOTE
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="PGTCL-LOAD-PACKAGE"
>3.1. Using the Tcl Package Command</A
></H1
><P
>You can use the Tcl <TT
CLASS="LITERAL"
>package</TT
> command to load
the <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> library.
This is the recommended approach, especially if you have multiple
applications using <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> on your system.
For this to work, you need the <TT
CLASS="FILENAME"
>libpgtcl</TT
> library
and the <TT
CLASS="FILENAME"
>pkgIndex.tcl</TT
> package index file installed.
If these files are installed properly, your application can use:
</P><PRE
CLASS="PROGRAMLISTING"
>package require Pgtcl</PRE
><P>
to load the <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> library.
Or, if your application requires a specific version:
</P><PRE
CLASS="PROGRAMLISTING"
>package require Pgtcl 1.5</PRE
><P> </P
><P
>This is the preferred method for loading a package into a Tcl application,
however it does require some installation setup. Specifically, the library
and package index file must be installed into a subdirectory of the Tcl
<TT
CLASS="LITERAL"
>$auto_path</TT
> or <TT
CLASS="LITERAL"
>$tcl_pkgPath</TT
>
directories.
A typical location for installation of this package might be:
<TT
CLASS="FILENAME"
>/usr/lib/tcl8.4/pgtcl1.5/</TT
> .
(Note the subdirectory name (here <TT
CLASS="FILENAME"
>pgtcl1.5</TT
>), does
not need to match the library name, and by convention includes only
the two parts of the version. Tcl looks in all subdirectories
of its package library directory to find packages.)
Refer to the Tcl documentation on
<TT
CLASS="COMMAND"
>pkgMkIndex</TT
> for more details.</P
><P
>In addition to installing the <TT
CLASS="FILENAME"
>libpgtcl</TT
> library,
you must install the <TT
CLASS="FILENAME"
>libpq</TT
> library in a location
where it will be found by the system shared library loader. Just
installing <TT
CLASS="FILENAME"
>libpq</TT
> in the package directory along
with <TT
CLASS="FILENAME"
>libpgtcl</TT
> will not work.</P
><P
>On Unix-like systems, either install the <TT
CLASS="FILENAME"
>libpq</TT
> library
into a well-known system directory such as
<TT
CLASS="FILENAME"
>/usr/local/lib</TT
>, or install it somewhere else. If you
install it somewhere else, either modify the system loader configuration
(typically using a command like <TT
CLASS="COMMAND"
>ldconfig</TT
>), or use the
environment variable <TT
CLASS="ENVAR"
>LD_LIBRARY_PATH</TT
> to tell the system
loader where to find it.</P
><P
>On Windows systems, install the <TT
CLASS="FILENAME"
>libpq</TT
> library
into a directory named in the <TT
CLASS="ENVAR"
>PATH</TT
> environment variable.
It will also work if the <TT
CLASS="FILENAME"
>libpq</TT
> library is installed in
the same directory as the Tcl script interpreter <TT
CLASS="FILENAME"
>tclsh.exe</TT
>
or <TT
CLASS="FILENAME"
>wish.exe</TT
>.</P
><P
>Another option for installing the <TT
CLASS="FILENAME"
>libpq</TT
> library is
to place it in the <SPAN
CLASS="APPLICATION"
>pgtcl</SPAN
> package directory,
and use a modified package index file to load it.
Here is a <TT
CLASS="FILENAME"
>pkgIndex.tcl</TT
> package index file for
Windows systems which enables loading both libraries from the
package directory. (This file is included in the Windows binary
distribution, and in the source distribution as
<TT
CLASS="FILENAME"
>pkgIndex.tcl.win32</TT
>.)</P
><P
></P><PRE
CLASS="PROGRAMLISTING"
># Tcl package index file, version 1.1
# This is a modified package index file for Pgtcl on Windows. libpgtcl needs
# libpq, but libpq has to be found on PATH. So this modifies PATH before
# loading libpgtcl, then restores PATH after. This allows you to store
# both libpgtcl.dll and [b]libpq.dll in the package directory.
proc Pgtcl__load_with_path {dir} {
global env
set save_path $env(PATH)
append env(PATH) ";$dir"
load [file join $dir libpgtcl.dll]
set env(PATH) $save_path
}
package ifneeded Pgtcl 1.5.2 [list Pgtcl__load_with_path $dir]</PRE
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