Introduction
This is a library for TCL clipboards. Warning:
The implementation is extremely simple, and not very robust.
The idea is that you can store text in a buffer, manipulate it,
and then send it to output. The buffer allows you to change,
remove or insert text many times before producing the final output.
This helps in situations where you want to write the text in a
come-back-and-fix-it-later fashion. You do not need to know in advance
exactly what you will want to output. With "puts" you do not have this
flexibility, because when you "puts" something, it's gone.
A text buffer in this library is called a clipboard.
A clipboard is a tree of nodes. Each node can be one of the following:
- A text node, containing plain freeform text.
- A plug with a name. New nodes can be inserted into a plug
(they become child nodes of the plug), and plugs can be emptied
so you can alter their contents.
- A reference to another clipboard. You can refer to the same
clipboard multiple times. When generating code, this allows
you to create a fragment of code once, and output it multiple
times (sort of like a #define in C).
You can insert new text into a plug, or remove the contents of a plug.
Plugs are accessed by their name, which is assumed to be unique
within a clipboard.
When the clipboard is finally printed to output, the tree is
traversed depth-first and all encountered text is printed.
References to other clipboards are printed in the same way, recursively.
Although conceptually a clipboard is a tree, it is implemented in TCL
as an array. The names of plug points are the entries into the array.
These names are mapped to a list of nodes, each of which is a tuple
starting with a specific letter: 't' for text nodes, 'p' for plugs,
'r' for references.
Refer to the examples to see how it all works:
- example1.tcl:
Using the basic clipboard procedures.
The output of running this script is in
out1.txt.
- example2.tcl:
Using a more intuitive interface, we build nested structures
in which the clipboard text is stored.
The output of running this script is in
out2.txt.
- example3.tcl:
Gives a brief impression of how clipboards can be used
in code generation (in this case, generating a C++ class).
The output of running this script is in
out3.txt.
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