week2

Question 1

concurrency

Answer 1

• ability to specify parts of program that can run simultaneously
• no assumption can be made about relative order of execution of concurrent portions of a program
• does not necessarily mean parallel
• even on multicore, no guarantee concurrent portion will be on different cores

Question 2

ada concurrency

Answer 2

task specifications

task body

Question 3

abstraction (func and types)

Answer 3

functions - procedural abstractions, hidden, i.e. printf for displaying output
types - data abstractions (bits)

Question 4

type

Answer 4

set of values w set of operations over those values

Question 5

adt

Answer 5

• type
• has complicated representation that is not visible to users of the type
• has user defined operations over values of the type

Question 6

higher order functions

Answer 6

functions that operate over functions

- pass func as parameter, insert into data struct and return func as parmeters

Question 7

static scoping

Answer 7

look where function is DEFINED

Question 8

dynamic chain

Answer 8

• represents the way back to the stack frame

Question 9

stacks in concurrency

Answer 9

cactus stack

each thread has its own stack

Question 10

stack pointer

Answer 10

• points to top of stack

- adjusted everytime something pushed on

Question 11

frame pointer

Answer 11

• points into same plc w/in current activation record
• locals and parameters are offset from FP in current AR
• when stack is decremented to go to next stack item, must have pter (DL) to show where to go in next frame

Question 12

block structure

Answer 12

• function can access its own declared varaibles as well as outside variables

Question 13

dynamic link

Answer 13

• pts to previous AR

Question 14

static link

Answer 14

• for each procedure from AR of current procedure to procedure outside of it
• allows arbitrary nested programs in ADA
• main procedure does not have static link
• if multiple a’s static link pts to most recent a
• address in memory

Question 15

symbol table

Answer 15

compiler uses it so names /searching does not occur

Question 16

why is static chain efficient

Answer 16

all variables forced on appropriate plc on stack

Question 17

closure

Answer 17

• code pter
• static link
  = environment; i.e. path to retrieve nonlocal variables that the function needs
  -self-contained

Question 18

heap

Answer 18

• when stack is not enough; i.e. in scheme for returning functions as parameters means procedures can outlive procedure where it is declared
• languages that support returning functions that access nonlocal variables

Question 19

garbage collection

Answer 19

reclaims space in heap where variables are no longer needed

Question 20

formal parameter

Answer 20

the parameter in the function construction

Question 21

actual parameter

Answer 21

the parameter when the function is called

Question 22

pass by value

Answer 22

the value of actual param is copied into formal param (c, c++, java)

Question 23

pass by ref

Answer 23

any use of formal params in body to function is ref to actual param

Question 24

pass by val-result

Answer 24

copy in copy out

Question 25

pass by name

Answer 25

algol copy rule

• expression that is in the actual parameter is passed
• replace formal params by actual params
• expand func call into body of funct w formals replaced by actual params