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<RT-title
author="Thomas Walker Lynch"
date="2026-02-12"
<ol>
<li>Symbol subclass</li>
<li>Factory subclass</li>
- <li>Context subclass</li>
- <li>a <RT-code>null<RT-code> symbol</li>
+ <li>ContextMap subclass</li>
</ol>
</p>
</p>
<p>
- When a Symbol instance is garbage collected, it contacts the Symbol.Factory, so that its <RT-term>identity</RT-term> can be added to the Symbol.Factory's free list.
+ When a Symbol instance is garbage collected, it contacts the Symbol.Factory, so that its <RT-term>identity</RT-term> can be added to the Symbol.Factory's free set.
<p>
<h2><RT-code>Factory</RT-code></h2>
<p>The <RT-code>Factory</RT-code> has:
<ol>
<li><RT-code>counter</RT-code></li>
- <li><RT-code>free_list</RT-code></li>
+ <li><RT-code>free_set</RT-code></li>
</ol>
</p>
</p>
<p>
- The lowest counter value is zero. At time of <RT-code>Factory</RT-code> initialization the zero value is given as the identity for the <RT-code>SymbolSpace.null</RT-code> symbol. This initialization strategy assures the counter value remains the highest issued symbol identity even immediately after initialization.
+ The factory <RT-code>__init__</RT-code> method is given a variable name that is assigned to the identify zero symbol during init. Thus the factory is always in a consistent state and ready to be used after it is made.
</p>
<p>
- To add to the free list, first check the current <RT-code>counter</RT-code> value, If the count matches the identity of the newly freed Symbol instance, decremented the count. If the Counter's post decrement value is on the free list, it is removed from the free list and the count is decremented again, this repeats until the new decement count is not found on the free list. It is an error to attempt to free the null symbol, that of 0.
+ To add to the free set, first check the current <RT-code>counter</RT-code> value. If the count matches the identity of the newly freed Symbol instance, decrement the count. If the Counter's post decrement value is on the free set, it is removed from the free set and the count is decremented again. This repeats until the new decrement count is not found on the free set. It is an error to attempt to free the null symbol (identity 0).
</p>
- <h2>Context</h2>
- <p>
- Context is a map keyed on a symbol list. Such a symbol list is called a 'symbol context'. Each key maps to a <RT-code>Factory</RT-code>.
- </p>
+ <p>Typically a caller does not directly instantiate factories, but instead uses the ContextMap. When this convention is followed, all symbols belong to a context.
+ </p>
+
+ <h2>ContextMap</h2>
<p>
- A program creates a context by calling <RT-code>make</RT-code> while giving it a <RT-code>Symbol</RT-code> instance list. That list, in the order the symbols are given, is said to be a <RT-term>symbol context</RT-term>. The <RT-code>make</RT-code> routine returns a <RT-code>Factory</RT-code>. Thus the returned <RT-code>Factory</RT-code> instance is a <RT-term>context specific factory</RT-term>.
- </p>
+ A program makes a factory by calling <RT-code>ContextMap.make</RT-code> while giving <RT-code>make</RT-code> two arguments. The first is a <RT-code>Symbol</RT-code> instance list that serves as the <RT-term>context key</RT-term>. The second argument is a variable that will be assigned to the first symbol in said context. The <RT-code>make</RT-code> routine returns a <RT-code>Factory</RT-code>. Said <RT-code>Symbol</RT-code> instance list can be empty, this is the so called <RT-term>root context</RT-term>.
+ </p>
- <p>The program should never give <RT-code>make</RT-code> a <RT-term>symbol context</RT-term> that is already a key in the table. <RT-code>make</RT-code> can be guarded using <RT-code>read</RT-code>
+ <p>The program should never give <RT-code>make</RT-code> a <RT-term>context key</RT-term> that is already a key in the map. <RT-code>make</RT-code> can be guarded using <RT-code>read</RT-code>.
</p>
- <p>The <RT-code>read</RT-code> function is given a symbol context and returns the corresponding <RT-term>context specific factory</RT-term>, or none, if there isn't one.
+ <p>The <RT-code>read</RT-code> function is given a context key and returns the corresponding <RT-code>Factory</RT-code>, or none if there isn't one.
</p>
- <p>A symbol that is part of <RT-term>symbol context</RT-term> will never be garbage
- collected. Hence, a <RT-term>symbol context</RT-term> remains in the table even when it is not being used.
+ <p>A symbol that is part of a <RT-term>context key</RT-term> will never be garbage collected. Hence, a <RT-term>context key</RT-term> remains in the map even when it is not being used.
</p>
- <p>A <RT-term>symbol context</RT-term> is deleted from the table by calling the <RT-code>delete</RT-code> interface function and giving it the <RT-term>symbol context</RT-term> to be deleted.</p>
+ <p>A <RT-term>context key</RT-term> is deleted from the map by calling the <RT-code>delete</RT-code> interface function and giving it the <RT-term>context key</RT-term> to be deleted.</p>
+
+ <h2>Instantiating a SymbolSpace</h2>
+ <p>
+ The SymbolSpace initializer is given a variable that serves as the first symbol to be made, and an optional context which serves as the first context to be made. The context defaults to the empty list.
+ </p>
<h1>Usage</h1>
- <p>A programmer first creates a <RT-code>SymbolSpace</RT-code>, then in normal use, the programmer will create a top level symbol to serve as a namespace. The programmer will then use the resulting <RT-term>context specific factory</RT-term> to create symbols within that namespace
+ <p>A programmer first creates a <RT-code>SymbolSpace</RT-code>. Then, in normal use, the programmer will create a top level symbol to serve as a namespace. The programmer will then use the resulting <RT-code>Factory</RT-code> to create symbols within that namespace.
</p>
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