Add Java Factory pattern tutorial on literate programming

requirements.txt

@@ -0,0 +1,9 @@
+certifi==2025.10.5
+charset-normalizer==3.4.4
+idna==3.11
+lxml==5.4.0
+Pygments==2.19.2
+PySnooper==1.2.3
+requests==2.32.5
+urllib3==2.5.0
+weblogin==1.11

src/Makefile

@@ -1,5 +1,5 @@
 .PHONY: all
-all: lpbook.pdf lpbook-teachers.pdf slides.pdf
+all: lpbook.pdf lpbook-teachers.pdf slides-intro.pdf slides-tutorial-java.pdf
 
 LATEXFLAGS+=	-shell-escape
 
@@ -14,6 +14,7 @@ SRC+=		test_introsort.py
 SRC+=		tests_Makefile
 SRC+=		cppjava.tex noweb.tex
 SRC+=		gdb.tex
+SRC+=		factory.tex
 
 FIGS+=		figs/pbr.png figs/pbrcover.jpg
 FIGS+=		figs/jupyter-lab.png figs/jupyter-notebook.png
@@ -26,6 +27,9 @@ SRC+=		fracexample2.cpp
 DEPENDS+=	FracExample.class
 SRC+=		Fraction2.java
 
+DEPENDS+=	DocumentExample.class DocumentFactoryTest.class
+SRC+=		DocumentFactory2.java
+
 SRC+=		weblogin.tex
 SRC+=		../weblogin/doc/contents.tex
 
@@ -38,14 +42,20 @@ fracexample2.cpp: cppjava.nw
 Fraction2.java: cppjava.nw
 	${NOTANGLE}
 
+DocumentFactory2.java: factory.nw
+	${NOTANGLE}
+
 lpbook.pdf: lpbook.tex didactic.sty
 lpbook.pdf: ${SRC} ${FIGS} ${DEPENDS}
 
 lpbook-teachers.pdf: lpbook-teachers.tex didactic.sty
 lpbook-teachers.pdf: ${SRC} ${FIGS} ${DEPENDS}
 
-slides.pdf: slides.tex didactic.sty
-slides.pdf: ${SRC} ${FIGS} ${DEPENDS}
+slides-intro.pdf: slides-intro.tex didactic.sty
+slides-intro.pdf: ${SRC} ${FIGS} ${DEPENDS}
+
+slides-tutorial-java.pdf: slides-tutorial-java.tex didactic.sty
+slides-tutorial-java.pdf: ${SRC} ${FIGS} ${DEPENDS}
 
 ${FIGS}::
 	${MAKE} -C $(dir $@) $(notdir $@)
@@ -66,7 +76,7 @@ test_introsort.py: introsort.nw
 
 .PHONY: clean
 clean:
-	${RM} lpbook.pdf lpbook-teachers.pdf slides.pdf
+	${RM} lpbook.pdf lpbook-teachers.pdf slides-intro.pdf slides-tutorial-java.pdf
 	${RM} merge.tex merge.sh
 	${RM} merge.aux merge.fdb_latexmk merge.fls merge.log
 	${RM} introsort.py introsort.tex
@@ -82,7 +92,11 @@ clean:
 frac.mk: cppjava.nw
 	${NOTANGLE.mk}
 
+factory.mk: factory.nw
+	${NOTANGLE.mk}
+
 include frac.mk
+include factory.mk
 
 INCLUDE_MAKEFILES=../makefiles
 include ${INCLUDE_MAKEFILES}/tex.mk

src/contents.tex

@@ -36,6 +36,7 @@
 }
 \mode<article>{\input{doctest.tex}}
 \mode<article>{\input{cppjava.tex}}
+\mode<article>{\input{factory.tex}}
 \mode<article>{\input{noweb.tex}}
 \mode<article>{\input{weblogin.tex}}
 

src/cppjava.nw

@@ -884,13 +884,21 @@ NOTANGLE.java=notangle -L'//line %L "%F"%N' -R$@ $< \
 
 \begin{frame}[fragile]
 Now let's turn to the [[COMPILE.java]] variable.
-As with other such variables, we'll use [[JAVAC]] and [[JAVACFLAGS]] to specify 
+As with other such variables, we'll use [[JAVAC]] and [[JAVACFLAGS]] to specify
 the compiler and its flags.
 We add the corresponding [[-L]] flag to [[noerr.pl]] in [[JAVACEXTRAS]].
+
+However, there is one important detail we must consider:
+[[javac]] writes error messages to stderr (as it should), but [[noerr.pl]] reads
+from stdin via the pipe.
+Since the pipe operator [[|]] only redirects stdout by default, we need to use
+[[2>&1]] to redirect stderr to stdout.
+This ensures that error messages flow through the pipe to [[noerr.pl]] for
+proper line number translation.
 <<frac variable definitions>>=
 JAVAC=        javac
 JAVACFLAGS=
-JAVACEXTRAS=  | noerr.pl -L'//line %L \"%F\"%N'
+JAVACEXTRAS=  2>&1 | noerr.pl -L'//line %L \"%F\"%N'
 COMPILE.java= ${JAVAC} ${JAVACFLAGS} $< ${JAVACEXTRAS}
 @
 \end{frame}