Make dviread.Dvi a context manager

jkseppan · jkseppan · commit e9f85716aaae · 2015-10-04T11:49:04.000+03:00
so files get closed automatically

Available in Python 2.5 and up
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -1845,9 +1845,8 @@ def draw_tex(self, gc, x, y, s, prop, angle, ismath='TeX!', mtext=None):
         texmanager = self.get_texmanager()
         fontsize = prop.get_size_in_points()
         dvifile = texmanager.make_dvi(s, fontsize)
-        dvi = dviread.Dvi(dvifile, 72)
-        page = six.next(iter(dvi))
-        dvi.close()
+        with dviread.Dvi(dvifile, 72) as dvi:
+            page = six.next(iter(dvi))
 
         # Gather font information and do some setup for combining
         # characters into strings. The variable seq will contain a
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
@@ -6,16 +6,16 @@
 
 Interface::
 
-  dvi = Dvi(filename, 72)
-  # iterate over pages (but only one page is supported for now):
-  for page in dvi:
-      w, h, d = page.width, page.height, page.descent
-      for x,y,font,glyph,width in page.text:
-          fontname = font.texname
-          pointsize = font.size
-          ...
-      for x,y,height,width in page.boxes:
-          ...
+  with Dvi(filename, 72) as dvi:
+      # iterate over pages (but only one page is supported for now):
+      for page in dvi:
+          w, h, d = page.width, page.height, page.descent
+          for x,y,font,glyph,width in page.text:
+              fontname = font.texname
+              pointsize = font.size
+              ...
+          for x,y,height,width in page.boxes:
+              ...
 
 """
 from __future__ import (absolute_import, division, print_function,
@@ -75,6 +75,12 @@ def _get_baseline(self, filename):
                 return float(depth)
         return None
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, etype, evalue, etrace):
+        self.close()
+
     def __iter__(self):
         """
         Iterate through the pages of the file.
@@ -910,15 +916,15 @@ def _vffile(texname):
     fname = sys.argv[1]
     try: dpi = float(sys.argv[2])
     except IndexError: dpi = None
-    dvi = Dvi(fname, dpi)
-    fontmap = PsfontsMap(find_tex_file('pdftex.map'))
-    for page in dvi:
-        print('=== new page ===')
-        fPrev = None
-        for x,y,f,c,w in page.text:
-            if f != fPrev:
-                print('font', f.texname, 'scaled', f._scale/pow(2.0,20))
-                fPrev = f
-            print(x,y,c, 32 <= c < 128 and chr(c) or '.', w)
-        for x,y,w,h in page.boxes:
-            print(x,y,'BOX',w,h)
+    with Dvi(fname, dpi) as dvi:
+        fontmap = PsfontsMap(find_tex_file('pdftex.map'))
+        for page in dvi:
+            print('=== new page ===')
+            fPrev = None
+            for x,y,f,c,w in page.text:
+                if f != fPrev:
+                    print('font', f.texname, 'scaled', f._scale/pow(2.0,20))
+                    fPrev = f
+                print(x,y,c, 32 <= c < 128 and chr(c) or '.', w)
+            for x,y,w,h in page.boxes:
+                print(x,y,'BOX',w,h)
diff --git a/lib/matplotlib/texmanager.py b/lib/matplotlib/texmanager.py
@@ -673,10 +673,7 @@ def get_text_width_height_descent(self, tex, fontsize, renderer=None):
         else:
             # use dviread. It sometimes returns a wrong descent.
             dvifile = self.make_dvi(tex, fontsize)
-            dvi = dviread.Dvi(dvifile, 72 * dpi_fraction)
-            try:
+            with dviread.Dvi(dvifile, 72 * dpi_fraction) as dvi:
                 page = next(iter(dvi))
-            finally:
-                dvi.close()
             # A total height (including the descent) needs to be returned.
             return page.width, page.height + page.descent, page.descent
diff --git a/lib/matplotlib/textpath.py b/lib/matplotlib/textpath.py
@@ -313,10 +313,8 @@ def get_glyphs_tex(self, prop, s, glyph_map=None,
         else:
             dvifile = texmanager.make_dvi(s, self.FONT_SCALE)
             dvi = dviread.Dvi(dvifile, self.DPI)
-        try:
+        with dvi:
             page = next(iter(dvi))
-        finally:
-            dvi.close()
 
         if glyph_map is None:
             glyph_map = dict()
