Skip to content

Wording to address #370 #499

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
davidherbert2 wants to merge 3 commits into from
Closed

Wording to address #370 #499

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
d21066e
adding clarification aboutr references (#370)
davidherbert2 Oct 5, 2020
24fd2a2
Slightly better wording
davidherbert2 Oct 5, 2020
46f45c0
Wording of references/relevance to lists (#370)
davidherbert2 Oct 5, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 19 additions & 4 deletions _episodes/03-types-conversion.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -186,10 +186,23 @@ three squared is 9.0

## Variables only change value when something is assigned to them.

* If we make one cell in a spreadsheet depend on another,
and update the latter,
the former updates automatically.
* This does **not** happen in programming languages.
Most of the time, variable assignment creates a new storage location for the value, so in this simple example:

~~~
a = 1
b = a
a = 2
print('a is', a, 'and b is', b)
~~~
{: .language-python}
~~~
a is 2 and b is 1
~~~
{: .output}

`b` is a **copy** of `a`, a separate storage location, so subsequent assignment of a new value to `a` leaves `b` completely unaffected.

Here is a slightly more complicated example involving computation on the second value:

~~~
first = 1
Expand All @@ -207,6 +220,8 @@ first is 2 and second is 5
creates a new value, and assigns it to `second`.
* After that, `second` does not remember where it came from.

Sometimes, however (e.g. with Python list types, described in more detail in Episode 11:Lists - under section 'Copying (or Not)'), more than one variable *can* point to the same storage location. Think of a cell in a spreadsheet which depends on another cell. Updating the latter will automatically update the former. The dependent cell is actually a **reference** to the original, not a distinct copy of it.

> ## Fractions
>
> What type of value is 3.4?
Expand Down
⚡