From 432ea1e2c6c2e8a41e46b943c835e7bbe6179a91 Mon Sep 17 00:00:00 2001
From: "Dr. Martin Goik" <goik@hdm-stuttgart.de>
Date: Thu, 18 Apr 2019 16:34:11 +0200
Subject: [PATCH] Np slides generated for figures in qandasets
---
Doc/Sd1/languageFundamentals.xml | 141 ++++++++++++++-------
ws/Docbook/CustomLayer/slide/slideHdm.xsl | 4 +-
ws/Docbook/Preprocess/Xsl/docbook2html.xsl | 2 +-
3 files changed, 98 insertions(+), 49 deletions(-)
diff --git a/Doc/Sd1/languageFundamentals.xml b/Doc/Sd1/languageFundamentals.xml
index 1c78d3796..4520f894f 100644
--- a/Doc/Sd1/languageFundamentals.xml
+++ b/Doc/Sd1/languageFundamentals.xml
@@ -4459,18 +4459,24 @@ _____________________________________
</figure>
<qandaset defaultlabel="qanda" xml:id="sd1_qanda_expressionTypes">
- <title>Expressions and type</title>
+ <title><code language="java">int</code> to <code
+ language="java">short</code> assignment</title>
<qandadiv>
<qandaentry>
<question>
<para>Consider the following code segment:</para>
- <programlisting language="java">short a = 4; <co
- linkends="sd1_co_expressionTypeIntToShort-1"
- xml:id="sd1_co_expressionTypeIntToShort-1-co"/>
+ <figure xml:id="sd1_qanda_expressionTypesListing">
+ <title><code language="java">int</code> expression
+ assignment</title>
+
+ <programlisting language="java">short a = 4; <co
+ linkends="sd1_co_expressionTypeIntToShort-1"
+ xml:id="sd1_co_expressionTypeIntToShort-1-co"/>
short sum = a + 7; <co linkends="sd1_co_expressionTypeIntToShort-2"
- xml:id="sd1_co_expressionTypeIntToShort-2-co"/></programlisting>
+ xml:id="sd1_co_expressionTypeIntToShort-2-co"/></programlisting>
+ </figure>
<calloutlist>
<callout arearefs="sd1_co_expressionTypeIntToShort-1-co"
@@ -4493,33 +4499,26 @@ short sum = a + 7; <co linkends="sd1_co_expressionTypeIntToShort-2"
<para>On contrary the following line will compile
flawlessly:</para>
- <programlisting language="java">short sum = 4 + 7;</programlisting>
+ <figure xml:id="sd1_listing_staticShortAssignment">
+ <title>Constant expression assignment</title>
+
+ <programlisting language="java">short sum = 4 + 7;</programlisting>
+ </figure>
<para>Explain this strange behaviour.</para>
</question>
<answer>
- <para>The expression <code language="java">a + 7</code> contains a
- variable <quote>a</quote> of type <code language="java"
- xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-B">short</code>
- to the plus operator's left and an <code language="java"
- xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-C">int</code>
- literal <quote>7</quote> to its right. Thus the plus operator
- yields an <code language="java"
- xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-C">int</code>
- result (the <quote>biggest</quote> type of both operands) which
- cannot be assigned to the variable <code
- language="java">sum</code> of type <code language="java"
- xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-B">short</code>.</para>
-
- <para>The very same argument seems to apply for the expression
- <code language="java">4 + 7</code> even more: This time the plus
- operator acts on even two <code language="java"
+ <para>Considering <code language="java">short sum = 4 + 7</code>
+ the plus operator acts on two <code language="java"
xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-C">int</code>
- operands. However in contrast to the former assignment this time
- <emphasis>both</emphasis> operands are static. The 4 + 7
- expression's value of 11 is being calculated at compile time.
- Since 11 of type <code language="java">int</code> is within
+ operands. Thus the expression <code language="java">4 + 7</code>
+ is of type <code language="java">int</code>. Both operands are
+ static <abbrev>i.e.</abbrev> their values are known at
+ <emphasis>compile time</emphasis> (rather than at <emphasis>run
+ time</emphasis>). The <code language="java">4 + 7</code>
+ expression's value can thus be evaluated at compile time. The
+ resulting value of <code language="java">11</code> is within
<inlineequation>
<m:math display="inline">
<m:mrow>
@@ -4558,11 +4557,61 @@ short sum = a + 7; <co linkends="sd1_co_expressionTypeIntToShort-2"
<m:mo>]</m:mo>
</m:mrow>
</m:math>
- </inlineequation> the compiler will safely cast this value to
- the <code language="java"
+ </inlineequation> so the compiler will safely cast and assign it
+ to the variable <code language="java">sum of type</code> <code
+ language="java"
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-B">short</code>
+ without any information loss.</para>
+
+ <para>The expression <code language="java">a + 7</code> contains a
+ variable <quote>a</quote> of type <code language="java"
xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-B">short</code>
- variable <code language="java">sum</code> without information
- loss.</para>
+ to the plus operator's left and an <code language="java"
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-C">int</code>
+ literal <quote>7</quote> to its right. Thus the expression is of
+ type <code language="java"
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-C">int</code>
+ as well. However a compiler will consider the variable <code
+ language="java">a</code>'s value to be unknown within the given
+ expression at compile time (albeit humans will safely assume a
+ value of 4 by virtue of the preceding statement). Therefore
+ variable <code language="java">a</code>'s value could potentially
+ exceed a <code language="java"
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.1-100-B">short</code>'s
+ range of values and thus cannot be assigned to the variable <code
+ language="java">sum</code> in a safe manner.</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+
+ <qandaset defaultlabel="qanda" xml:id="sd1_qanda_expressionTypesFinal">
+ <title><code language="java">int</code> to <code
+ language="java">short</code> assignment using <code
+ language="java">final</code></title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>We reconsider a variant of <xref
+ linkend="sd1_qanda_expressionTypesListing"/>:</para>
+
+ <programlisting language="none"><emphasis role="red">final</emphasis> short a = 4;
+short sum = a + 7;</programlisting>
+
+ <para>This time the code compiles flawlessly. Explain the
+ underlying reason being related to the <code
+ language="java">final</code> modifier's role.</para>
+ </question>
+
+ <answer>
+ <para>A final variable's value cannot change. Thus the expression
+ a + 7 is fully equivalent to 4 + 7 and can thus be evaluated at
+ <emphasis>compile time</emphasis>. Like in the preceding <xref
+ linkend="sd1_listing_staticShortAssignment"/> code sample the
+ resulting value of <code language="java">11</code> neatly fits
+ into the variable <code language="java">sum</code> of type <code
+ language="java">short</code>.</para>
</answer>
</qandaentry>
</qandadiv>
@@ -5193,7 +5242,7 @@ System.out.println("Difference: " + difference);</programlisting><screen>Differe
</qandaset>
<qandaset defaultlabel="qanda" xml:id="sw1QandaCircleAreaFinal">
- <title>Calculating the area of a circle avoiding accidental
+ <title>Calculating a circle's area avoiding accidental
redefinition</title>
<qandadiv>
@@ -5213,8 +5262,8 @@ System.out.println("Difference: " + difference);</programlisting><screen>Differe
}</programlisting>
<para>Though there is nothing wrong with this approach it is error
- prone: In a similar program a careless programmer accidentally
- redefine the value of <code language="java">pi</code>:</para>
+ prone: A careless programmer might accidentally redefine the value
+ of <code language="java">pi</code>:</para>
<programlisting language="java">double pi = 3.141592653589793;
@@ -5280,7 +5329,7 @@ System.out.println("A circle of radius " + radius + " will cover an area of " +
time error:</para>
<para><computeroutput>Cannot assign a value to final variable
- 'PI'</computeroutput></para>
+ 'pi'</computeroutput></para>
</callout>
</calloutlist>
@@ -5289,8 +5338,8 @@ System.out.println("A circle of radius " + radius + " will cover an area of " +
xlink:href="https://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.12.4">final</code>
declaring it to remain constant.</para>
- <para>In addition we may refactor our variable <code
- language="java">pi</code> to use capital letters reflecting the
+ <para>In addition refactoring our variable <code
+ language="java">pi</code> using capital letters reflecting the
naming convention for constants. This is does not change program
execution in any way but enhances code readability:</para>
@@ -5300,7 +5349,7 @@ double radius = 2.3; // Computing a circle's area
System.out.println("A circle of radius " + radius + " will cover an area of " +
<emphasis role="red">PI</emphasis> * radius * radius);
-<emphasis role="red">PI</emphasis> = -4;
+<emphasis role="red">PI</emphasis> = -4; <emphasis role="red">// Compile time error</emphasis>
radius = 1.8;
@@ -5359,22 +5408,22 @@ final int secondsElapsed =
System.out.println(secondsElapsed);</programlisting>
- <para>This requires four additions and 10 multiplications. We may
- use:</para>
+ <para>This requires four additions and 10 multiplications. <link
+ xlink:href="https://eli.thegreenplace.net/2010/03/30/horners-rule-efficient-evaluation-of-polynomials#horner-s-rule">Horner's
+ rule</link> allows for:</para>
<programlisting language="java">...
final int secondsElapsed =
seconds + 60 * (minutes + 60 * (hours + 24 * (days + 7 * weeks)));
...</programlisting>
- <para>This leaves us with four additions but just 4 instead of 10
- multiplications.</para>
+ <para>This still leaves us with four additions but just 4 instead
+ of 10 multiplications.</para>
<para>Within the given context the difference in execution time
- can be neglected. But in a different application the calculation
- in question might have to be repeated millions of times giving
- rise to a substantial gain with respect to total execution
- time.</para>
+ can be neglected. But in a larger application the calculation in
+ question might have to be repeated millions of times giving rise
+ to a substantial gain with respect to execution time.</para>
</answer>
</qandaentry>
</qandadiv>
@@ -5540,7 +5589,7 @@ System.out.println("A circle of radius " + radius + " will cover an area of " +
<qandadiv>
<qandaentry>
<question>
- <para>This exercise consists of two parts:</para>
+ <para>This is a two part exercise:</para>
<orderedlist>
<listitem>
diff --git a/ws/Docbook/CustomLayer/slide/slideHdm.xsl b/ws/Docbook/CustomLayer/slide/slideHdm.xsl
index b81a3ec62..a5390eb29 100644
--- a/ws/Docbook/CustomLayer/slide/slideHdm.xsl
+++ b/ws/Docbook/CustomLayer/slide/slideHdm.xsl
@@ -58,7 +58,7 @@
<div class="reveal">
<!-- Wrap all slides in a single "slides" class -->
<div class="slides">
- <xsl:apply-templates select=".//d:figure" mode="slideDescendants"/>
+ <xsl:apply-templates select=".//d:figure[not (ancestor::d:qandaset)]" mode="slideDescendants"/>
</div>
</div>
@@ -222,7 +222,7 @@
<xsl:variable name="currentFigureId" select="generate-id()"/>
<xsl:variable name="followupQandasets"
- select="following::d:qandaset[generate-id(preceding::d:figure[1]) = $currentFigureId]"/>
+ select="following::d:qandaset[generate-id(preceding::d:figure[not(ancestor::d:qandaset)][1]) = $currentFigureId]"/>
<xsl:if test="$followupQandasets">
<xsl:if test="10 < count($followupQandasets)">
diff --git a/ws/Docbook/Preprocess/Xsl/docbook2html.xsl b/ws/Docbook/Preprocess/Xsl/docbook2html.xsl
index 02888ad7b..636e2ad68 100644
--- a/ws/Docbook/Preprocess/Xsl/docbook2html.xsl
+++ b/ws/Docbook/Preprocess/Xsl/docbook2html.xsl
@@ -27,7 +27,7 @@
</xsl:template>
- <xsl:template match="db:figure/db:title">
+ <xsl:template match="db:figure[not(ancestor::db:qandaset)]/db:title">
<xsl:variable name="slideContainerId" select="ancestor::*[contains(@annotations, 'slide')]/@xml:id"/>
<title>
--
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