Safe Data Structures (Array, Hash, Struct)
safestruct gem / library - safe data structures (array, hash, struct) - say goodbye to null / nil (and maybe) - say hello to zero
- home :: github.com/s6ruby/safestruct
- bugs :: github.com/s6ruby/safestruct/issues
- gem :: rubygems.org/gems/safestruct
- rdoc :: rubydoc.info/gems/safestruct
Usage
Safe Struct • Safe Array • Safe Hash
Null / Nil - The Billion Dollar Mistake ++ Zero - The Billion Dollar Fix
I call it my billion-dollar mistake. It was the invention of the null reference in 1965. At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W). My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler. But I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years.
Let's make the code safer and let's say goodbye to null / nil (and maybe). How can the code work without nil?
Let's say hello to zero. The new rule for NO null/nil ever (again) is:
All variables - including structs, arrays and hash mappings - MUST ALWAYS get set (initialized) to ZERO (default) values.
What's zero?
Type | Value |
---|---|
Integer | 0 or Integer.zero |
Bool | false or Bool.zero |
String | '' or String.zero |
Array | [] or Array.zero |
Hash | {} or Hash.zero |
Vote (Struct) | Vote.new( 0, false, 0, '0x0000') or Vote.zero |
Address | 0x0000 or Address.zero or Address(0) |
... |
Safe Struct
Let's you define (auto-build) new struct classes. Example:
SafeStruct.new( 'Voter', weight: 0, voted: false, vote: 0, delegate: '0x0000' )
voter1 = Voter.new # or Voter.new_zero
voter1.weight #=> 0
voter1.voted? #=> false
voter1.vote #=> 0
voter1.delegate #=> '0x0000'
voter1.frozen? #=> false
voter1 == Voter.zero #=> true
voter1 == Voter(0) #=> true
voter1.delegate = '0x1111'
voter1 == Voter.zero #=> false
voter2 = Voter.new( 0, false, 0, '0x0000')
voter2.voted = true
voter2.delegate = '0x2222'
voter2 == Voter.zero #=> false
Voter.zero.frozen? #=> true
voter3 = Voter.new( 0 ) #=> ArgumentError: wrong number of arguments
# for Voter.new - 1 for 4
Note: You can use Struct
as an alias for SafeStruct
(in the Safe
namespace) or use the struct
class method macro:
struct( :Voter, weight: 0, voted: false, vote: 0, delegate: '0x0000')
# or
struct :Voter, { weight: 0, voted: false, vote: 0, delegate: '0x0000' }
# or
struct :Voter, weight: 0, voted: false, vote: 0, delegate: '0x0000'
# or
struct :Voter,
weight: 0,
voted: false,
vote: 0,
delegate: '0x0000'
Safe Array
Let's you define (auto-build) new (type safe) array classes. Example:
ArrayInteger = SafeArray.build_class( Integer )
ary = ArrayInteger.new
ary.size #=> 0
ary[0] #=> IndexError: index 0 outside of array bounds
ary.size = 2 #=> [0,0]
ary[0] #=> 0
or use the Array.of
convenience shortcut:
ary = Array.of( Integer )
ary.size #=> 0
ary[0] #=> IndexError: index 0 outside of array bounds
ary.size = 2 #=> [0, 0]
ary[0] #=> 0
## or
another_ary = Array.of( Bool )
another_ary.size #=> 0
another_ary[0] #=> IndexError: index 0 outside of array bounds
another_ary.size = 2 #=> [false, false]
another_ary[0] #=> false
## or
another_ary = Array.of( Bool, 2 )
another_ary.size #=> 2
another_ary[0] #=> false
Yes, Safe Array works with structs (or nested arrays or hash mappings) too. Example:
ary = Array.of( Vote )
ary[0] #=> IndexError: index 0 outside of array bounds
ary.size = 2 #=> [#<Vote @weight=0, @voted=false, @vote=0, @delegate='0x0000'>,
# #<Vote @weight=0, @voted=false, @vote=0, @delegate='0x0000'>]
ary[0] #=> #<Vote @weight=0, @voted=false, @vote=0, @delegate='0x0000'>
ary[0].voted? #=> false
Safe Hash
Let's you define (auto-build) new (type safe) hash classes. Example:
Hash_X_Integer = SafeHash.build_class( String, Integer )
hash = Hash_X_Integer.new
hash['0x0000'] #=> 0
or use the Hash.of
convenience shortcut:
hash = Hash.of( String => Integer )
hash['0x0000'] #=> 0
hash['0x0000'] += 42
hash['0x0000'] #=> 42
Note: Safe Hash will ALWAYS return a value.
If the key is missing in the hash mapping on lookup,
the key gets auto-added with a zero value.
Use has_key?
or key?
to check if a key is present (or missing).
Yes, Safe Hash works with structs (or arrays or nested hash mappings) too. Example:
hash = Hash.of( String => Vote )
hash['0x0000'] #=> #<Vote @weight=0, @voted=false, @vote=0, @delegate='0x0000'>
hash['0x0000'].voted? #=> false
hash['0x0000'].voted = true
hash['0x0000'].voted? #=> true
# or
allowances = Hash.of( String => Hash.of( String => Integer ) )
allowances['0x1111']['0xaaaa'] = 100
allowances['0x1111']['0xbbbb'] = 200
allowances['0x2222']['0xaaaa'] = 300
allowances['0x1111']['0xaaaa'] #=> 100
allowances['0x1111']['0xbbbb'] #=> 200
allowances['0x2222']['0xaaaa'] #=> 300
allowances['0x2222'].delete( '0xaaaa' )
allowances['0x2222']['0xaaaa'] #=> 0
Bonus: Auto-Generated Unicode (UTF-8) Class Constants / Names for Pretty Printing
Did you know? Yes, you can use unicode characters in your identifiers. The safe data structures library auto-generates unicode class constants / names for pretty printing and more. Examples:
Class Builder | Class Constant / Name |
---|---|
Array.of( Integer ) |
Array‹Integer› |
Array.of( Bool ) |
Array‹Bool› |
Array.of( Bool, 2 ) |
Array‹Bool›×2 |
Array.of( Vote ) |
Array‹Vote› |
Array.of( Array.of( Integer, 3), 3 ) |
Array‹Array‹Integer›×3›×3 |
Hash.of( String => Integer ) |
Hash‹String→Integer› |
Hash.of( String => Vote ) |
Hash‹String→Vote› |
Hash.of( String => Hash.of( String => Integer )) |
Hash‹String→Hash‹String→Integer›› |
... |
Note, and yes if the typing is not too much - you can use the "magic" names in your code too. Example:
ary = Array‹Integer›.new
ary.size #=> 0
ary[0] #=> IndexError: index 0 outside of array bounds
ary.size = 2 #=> [0,0]
ary[0] #=> 0
# or
another_ary = Array‹Bool›×2.new
another_ary.size #=> 2
another_ary[0] #=> false
# or
hash = Hash‹String→Integer›.new
hash['0x0000'] #=> 0
hash['0x0000'] += 42
hash['0x0000'] #=> 42
# or
allowances = Hash‹String→Hash‹String→Integer››.new
allowances['0x1111']['0xaaaa'] = 100
allowances['0x1111']['0xbbbb'] = 200
allowances['0x2222']['0xaaaa'] = 300
and so on.
What about Safe Enumeration (Integer) Types?
Yes, yes, yes. The Enum
class from the enums library gets auto-required.
Use like:
Enum.new( 'Color', :red, :green, :blue )
## or
enum 'Color', :red, :green, :blue
## or
enum 'Color', [:red, :green, :blue]
See the enums library documentation for more »
More "Real World" Safe Data Structures (Array, Hash, Struct) Samples
- The "Red Paper" about sruby - Small, Smart, Secure, Safe, Solid & Sound (S6) Ruby - The Ruby Programming Language for Contract / Transaction Scripts on the Blockchain World Computer - Yes, It's Just Ruby
- Programming Crypto Blockchain Contracts Step-by-Step Book / Guide. Let's Start with Ponzi & Pyramid Schemes. Run Your Own Lotteries, Gambling Casinos and more on the Blockchain World Computer...
- Ruby Sample Contracts for the Universum Blockchain/World Computer Runtime
License
The safestruct
scripts are dedicated to the public domain.
Use it as you please with no restrictions whatsoever.
Questions? Comments?
Send them along to the wwwmake forum. Thanks!