Add basic material on with statements.

3 files changed, 170 insertions, 5 deletions

diff --git a/advanced_python/18_with_statement.ipyml b/advanced_python/18_with_statement.ipyml
new file mode 100644
index 0000000..b231d39
--- /dev/null
+++ b/advanced_python/18_with_statement.ipyml
@@ -0,0 +1,167 @@
+cells:
+
+- markdown: |
+    # Advanced Python: `with` statements
+
+    ### Prabhu Ramachandran
+    ### The FOSSEE Python group &
+    ### Department of Aerospace Engineering
+    ### IIT Bombay
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- markdown: |
+    ## Introduction
+
+    - `with` statement is used as follows
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    with open('data/test.txt') as f:
+        for line in f:
+            print(line, end='')
+
+  id: 0
+
+- code: |
+    f.closed
+
+  id: 1
+  metadata:
+    slideshow:
+      slide_type: fragment
+
+- markdown: |
+    ## Observations
+
+    - Creates a context
+    - `f` is automatically closed
+    - Works even if there was an exception!
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- markdown: |
+    ## Use cases
+
+    - Use it with locks (for threaded computing)
+    - Database connections
+    - File objects
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- markdown: |
+    ## Creating your own
+
+    - Relatively easy to do
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- code: |
+    from contextlib import contextmanager
+
+    @contextmanager
+    def context():
+        print("setup")
+        try:
+            yield
+        finally:
+            print("done")
+
+- code: |
+    with context():
+        print("do something")
+
+- markdown: |
+    ## A more complex example
+
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+
+- code: |
+    import os
+    from contextlib import contextmanager
+
+    @contextmanager
+    def tempfile(filename):
+        f = open(filename, 'w')
+        try:
+            yield f
+        finally:
+            f.close()
+            os.remove(filename)
+
+- code: |
+    with tempfile('junk.txt') as f:
+        f.write('hello world\n')
+        f.flush()
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+- markdown: |
+    ## Comments
+
+    - Useful feature
+    - Can define an object supporting this
+    - Overload, `__enter__` and `__exit__`
+    - Not covered here
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+
+
+- markdown: |
+    ## More information
+
+    - https://www.python.org/dev/peps/pep-0343
+    - [With statement](https://docs.python.org/3/reference/datamodel.html#with-statement-context-managers)
+    - [Context manager types](https://docs.python.org/3/library/stdtypes.html#typecontextmanager)
+
+  metadata:
+    slideshow:
+      slide_type: slide
+
+# The lines below here may be deleted if you do not need them.
+# ---------------------------------------------------------------------------
+metadata:
+  kernelspec:
+    display_name: Python 3
+    language: python
+    name: python3
+  language_info:
+    codemirror_mode:
+      name: ipython
+      version: 3
+    file_extension: .py
+    mimetype: text/x-python
+    name: python
+    nbconvert_exporter: python
+    pygments_lexer: ipython3
+    version: 3.6.0
+  rise:
+    scroll: true
+    transition: none
+nbformat: 4
+nbformat_minor: 2
+
+# ---------------------------------------------------------------------------
+data:
+  [{execution_count: null, outputs: []}, {execution_count: null, outputs: []}, {execution_count: null,
+      outputs: []}, {execution_count: null, outputs: []}, {execution_count: null, outputs: []}]
diff --git a/advanced_python/data/test.txt b/advanced_python/data/test.txt
new file mode 100644
index 0000000..c100072
--- /dev/null
+++ b/advanced_python/data/test.txt
@@ -0,0 +1,3 @@
+hello
+world
+
diff --git a/advanced_python/rise.css b/advanced_python/rise.css
index 11d733d..0846e50 100644
--- a/advanced_python/rise.css
+++ b/advanced_python/rise.css
@@ -8,11 +8,6 @@ div.cell.code_cell {
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